1 Lucky Texan

interference engine, risky on the 2.5 to not replace the rollers in the TB system. The toothed idler is 'especially' prone to failure. you could test the thermostat on the stove, if it opens and closes smoothly at 170* F, re-use it. There is a Stant Xacstat that is OEM-style that is not crazy expensive. spark plugs are a little easier if you're also doing the VC gaskets. clean and re-use the PCV valve?

you didn't mention alignment - maybe the tow or other parameter is a little out-of-spec? there is a 'cardan' (?) or type of u-joint on the steering shaft that might create odd feelings in the steering wheel. Dunno about only at speed though - weird. a very common problem is also air in the power steering fluid - often caused by a bad o-ring at the suction hose adapter on top of the PS pump. But, also not usually reported to be at speed only..... some people have had worn rack bushings create problems. odd

most newer style require a quick bake in the oven. I'm sure you can find DIY stuff and even youtube videos.

not sure , but, if only the seals are bad - a rebuild might be just fine? others will know more. if you don't like what you hear from S-Wings, checkout out RetroRoo in Henderson ; http://retroroo.com/ Shawn will take of you I'm sure!

possible Engine Temp Sensor - doesn't 'choke' the car in the mornings. But I'd expect hard starting/poor idling until warm. on an older car, could be some type of temp sensitive vacuum leak. a vacuum gauge is cheap to buy, maybe free to borrow from a parts-place. Check when cold in the morning, compare to warm conditions? maybe a sticky valve in the failing misfiring cylinder? carbon buildup or dropped guide?

ThosL - even though the codes have definitions, if that definition mentions a specific part - it does not mean that part is automatically bad. As said above, further diagnosis is almost always required. But, given the cost/hassle of hiring a pro, it CAN sometimes still be 'practical' to change inexpensive, and maybe even moderately-priced parts while trying to troubleshoot our own cars. After all, even if you 'guess' wrong, you probably replaced a tired, old part with a new one and eliminated that part of the system as a failure. but, sometimes a code will point to a $200 sensor or an $800 catalytic converter - and people find the actual problem was some rodent-chewed wiring that can be repaired for a few dollars, or a hole in the exhaust that can be welded-up for $50. Other people may pay a GOOD mechanic to diagnose the car, then pull it back home and repair it themselves. many different approaches. And there's nothing wrong with having a pro fix your car. There are trade-offs in every approach, depending on your situation. Sometimes I don't have the luxury of time for extensive tear-down, even if I thought i had the skill. there's an old saw about; CHEAP, FAST ,GOOD - you can only choose 2.

if there is moisture in the mornigs, could be a cracked coil i guess. Also, look for oil on the wire boots. maybe leaky valve cover gaskets/oil shorting the high voltage.. (might not be a problem though on 2.2s ?)

p0420 can have a lot of causes, if the car has power-loss or other problems, I'd be tempted to address those first and hope the p0420 resolves after that. Sometimes a p0420 is only an exhaust leak - sometimes it really is a bad cat. conv. Converters are so expensive though - you want to eliminate every other possibility first. 302 is a misfire in cyl 2. many things can cause that, but of course plugs , plig wires would be the first place to look on an older car. Plugs should be NGK, wires should be OEM or Denso. vary from those and risks of problems increase a lot. many people have problems in that system with aftermarket parts. wires can sometimes be moved around. If the problem follws the wire to another cylinder - it's a bad wire. If not, could be a plug or burned valve or ???? Or bad wires/coils sometimes show up if squirted with a plant 'mister' of water at night while idling. any arcing is a failure in the wire or coil. Even looking at the plugs/comparing cylinders can be useful. An infrequently driven car, or car driven short distances can have a lot of carbon build-up in the cylinders.

yeah, GG is the source here - really helped me a lot.

not sure what the ECU's threshold is, but from what I've read, flashing supposedly means active, repeating misfiring is occurring - bad enough that catalytic converters may be damaged. A solid light + recorded misfires, might be a single occurrence, or perhaps a few misfires? but, i have no detailed information aside from that.

well, fresh struts are gonna feel a lot tighter. KYB is the preferred brand for most of us. a heavier rear anti-roll bar, maybe metal endlinks (less 'compliant') front and rear. kartboy or whiteline etc.

hard to say if your system is empty for a different reason but, there's 1 o-ring each on the suction and discharge hoses on my 03 Outback. So, 2 o-rings. look thru the thread I linked. You may need a pro but, the more common issues can be done fairly easily by a backyard mechanic.

often, the o-rings at the compressor-mounted ends of the suction and discharge hoses go bad. Since the system is discharged, fairly easy to change them, probably worth changing the valve-inserts at the hi and low ports. less commonly, the discharge hose itself is bad. probably start by putting 22-25ozs of refrigerant in after changing at least the o-rings. Consider using the refrig. with the dye in it. Fixed my Outback that way. see; http://www.ultimatesubaru.org/forum/topic/127980-diy-ac-air-conditioning-leak-refrigerant-repair-for-5-or-less15-m/

if the fuel system is open to the atmosphere - you can get a lot of water from condensation -MUCH worse if the car spends a lot of time at less than a full tank. (more moisture-laden air PLUS greater water:fuel ratio) I have no real experience with a soob that old. maybe someone else can chime in. But, if there is water in the fuel and/or rust on the pump's intake - that all needs to be addressed.

opportunity here to refresh the looks of the car with new rims!

you might install new brake hoses at the calipers. old one can 'balloon' a little making pedal feel somewhat softer. certainly wouldn't hurt to 'rock' each wheel up-down/12 oclock-6oclock but, even if there isn't movement, soob wheel bearings can be bad with no 'typical' symptoms.

clutches and brakes are wear items all cars need occasionally - you can't lay that on Subaru (now, maybe the dealership/mechanic sold you more parts than you needed, that has happened) it does kinda seem like Subaru suspension (well, struts anyway) is not extremely long-lasting, but it may depend a lot on use and climate. I could certainly understand being upset about early turbo failure - one of the reasons I run synthetic in my 06 WRX and change it often, is to do the most I can to hold off that expense. Too bad yours failed so soon.

rebuilt alternator could be bad - that system needs to be checked, overcharging a battery is not good. Could also be a bad/intermittent ground wire somewhere. They can need to be 'refreshed' on older cars. is the check engine light on? might check for pending codes anyway (is it OBD I ?, will the old system store pending codes?)

heat shields can definitely react the way you describe. It's a frequent complaint - but, kinda surprised the dealership didn't jump at a chance to charge you for their repair so - at this point, I think another opinion might be helpful. bad knock sensor might cause the engine to 'rattle' AND affect mileage, though I'd expect it to be worse on acceleration, not coming off. ask in a new thread for a recommendation and maybe someone near you in 'west by god' will know of a good shop.

gone?

confirm it isn't the timing belt flopping around due to a failed TB tensioner - can sound like rod knock, also, 'might' leave a 'rubbed' spot on the inside of the TB cover.

that'll buff right out.

it kinda looks like you should push it. If the cable is slack enough - worth a try. can you get your phone/camera or a mirror back there to take a pic? it might look different or show a tab or ???????? maybe visit a junkyard and practice on a wreck!

hopefully, you installed an OEM style t'stat. was coolant pushed out of the overflow? bubbling in the overflow or radiator is often a sign of a bad headgasket. there is a chemical test for bad HGs that a few people have found helpful. sometimes a leakdown test can find the bad cylinder. always check the fluid level in the radiator (safely, when cool enough of course) don't trust the level in the o'flow.

does your engine have HLAs or solid lifters? I have no experience buying injectors. I think you can get a fuel pressure tester on loan from a parts store. if you suspect a lot of debris in the tank, perhaps looking at the pump's 'sock' would be a cheap next step?