1 Lucky Texan

a REAL GM guy would know about this boxer;

yeah - might also depend on whether 1 or both fans are running, plus, keep in mind where the rad's intake and output hoses are. If it's working well in not too hot conditions, we might expect only part of the radiator's surface to be warm. The portion nearest to the inlet.

hmmmm....I once read of a waterpump that had much of its impeller blades corroded off - maybe by a previous owner running straight water? couldn't pump enough. is the car actually overheating? fans working?

inspect the tires too. - longshot heat shields? - they usually 'buzz' though driveline seems most likely

others will have experience - I've read that it is tricky to get good results from measuring different areas of our radiators. was an OEM-style thermostat used? the small, typical aftermarkets can cause problems. Also, pulling the top hose off and filling the block directly with coolant, then reconnecting and filling the radiator helps remove trapped air.

check the timing. you might pull the plugs after it sits overnight and see if one is wet - maybe an injector is leaking?

If there is foam/many bubbles then that MUST be addressed. (OK, to be clear, it IS possible to see pehaps one or 2 bubbles every few seconds cause by flow/turbulence from returning fluid) car must be idling. Wheel 'may' need to be turned by a helper while watching the fluid. There may be a whining sound, or, like my WRX, there may only be jerky-feeling steering wheel feedback or other symptom. There are few places air can get sucked in; the o-ring/o-rings (depending on the model of Outback) on top of the pump. The hose, failure of the clamps on the hose, a crack in the reservoir, a crack in the fitting that goes on top of the pump and maybe some problem inside the pump. I suppose the 'seat' for the o-ring could be scratched if someone wasn't careful removing the old o-ring. I used a toothpick to prevent gouging the area where the o-ring must seal. That's it. The rest of the system is under pressure and will leak fluid OUT, not suck air IN. I use the HNBR o-rings. They are kinda green/turqoise colored. Something else might be whining. The car will run briefly without accessory belt(s) - that might help locate a problem with A/C or alternator pulley bearings or tensioner bearings etc.

was there any oil on the plug wire boots? maybe a weak coil? a wet area could also have poor/corroded ground connections. Try refreshing ground connections.

06 WRX steering was vibrating (but no squealing). Foam in the reservoir - just like my 03 OBW. So, pulled the fitting off the top of the PS pump and swapped out the o-ring. The closest one I had may not last long, had to stretch it a bit and I am concerned it isn't 'fat' enough now. But I ordered a larger assortment set from ebay so, i should have those on hand if it fails again. Probably do maintenance type stuff in april on both cars. WRX is needing a timing belt according to the Months side of the schedule. i think I'll put that off till october.

overflow WILL need to come out. Look on the side, down low, of the radiator - probably right (US pass.) side. take the rad cap off for more vigorous flow - or go ahead and tale the upper rad hose loose - best to fill the block directly thru it, then connect and fill the rad.

you could try pairing the remotes again. look on cars101.com for those instructions. otherwise, I think the module in the car could be bad?The odds of having both remotes bad seems low to me. if you know someone with the same generation car, try pairing their working remote to your car and see if it works.

probably have to rely on fairtax or other gurus here - i have no experience with the TPS.

wait - it ONLY stumbles around 2000? it's OK at 2500, 3000, 3500, etc.? that seems like a Throttle Position Sensor issue, re-reading you original post, I'd say it's quite likely the TPS has a bad/dirty spot on it. Try replacing it. I THINK I've read of some folks using contact cleaner in them but I have no experience with that. I have no idea why that would show as retarded timing other than the ECU assuming you were at idle when it loses the correct throttle opnening percentage. sorry for my confusion/lack of reading skills.

if a crank or cam pulley is one, maybe 2 teeth off - they will run, just not well. you are either WAAAAYYYY overdue for a belt, or geting close to needing one (105K is your schedule I think) However, the fact that it seems to run well with the factory settings after a reset - would seem to support some air/fuel sensor problem. Though i don't understand why there's no code for an O2 sensor or something related. Does the monitor you have hooked up report fuel trims or other data? if this car has a MAF, you might try cleaning it with the correct solvent - but maybe you have MAP?

typo - LEANing out, not leak.

how many miles on the car? wondering if it's worth the trouble to check the cam/crank timing. (though, seems unlikely a battery reset to the ECU would restore fully normal perf.) If you could get the FreezeFrame data that some code readers produce, or get an elm327 device to use with Torque app on a smartphone - that data might be helpful.

unlikely the synth will cause any problems. there are many theories on this but, not a lot of real 'data'. wondering about the IACV hose.

any work done prior to this happening? did the car get a new timing belt 80K ago?

maybe the previous owner had synth in there. as mentioned above, get some name brand GL-5 non-synth, non-additive in there. If it still misbehaves severley, probably a trashed gear inside. You MIGHT be able to maybe it by 'double clutching' between gear changes, but a repair or tans swap might be best. As a last ditch effort, you could try Scotty's Cocktail as outlinmed in this huge thread at NASIOC; http://forums.nasioc.com/forums/showthread.php?t=920674 , but, the money spent on a coupla fluid changes might be better spent on a trans swap. (note, any trans swap MUST have a final drive that matches your rear diff)

there is a dipstick on the right (US pass.) side back near the firewall. Its yellow handle may be covered in grease. Consider having another driver try driving the car to see if they have the same issues shifting. I had to make 3-4 small seat adjustments, and drive for a a coupla weeks, in my WRX to get OK with the clutch/tranny. Still stall the car every 8-10 months w'ever. I try to get off the clutch in the first few inches/foot of travel. you could have a transmission problem. maybe get a mechanic to drive it. If the fluid is old, get some quality GL-5 or Subaru Extra-S in there. If it's already been replaced - but someone used a synthetic fluid, well, some people report problems with the synthetics not allowing the synchros to spin properly for smooth shifting. Sometimes problems with shifter bushing or motor/tranny mounts makes shifting tricky.

suppose the sensor has failed in such a way it prevents the ECU from pulling the timing. that is, there's knocking that is unreported. Then higher octane should remedy some of the knocking.

if the car has pulled timing due to 'real' knock or false readings from a bad KS, you will experience reduced performance. some folks have spotted cracks in the sensor. The FSM may have a test for it. They are cheap parts. maybe cheaper than 2-3 bottles of Techron if bought from ebay.

easy fix, just buy 14 rolls of black tape and cover the engine.

look for your car's instructions here; http://www.cars101.com/subaru/keyless.html#05%20legacy%20program%20remotes have you tried the other fob? should have been paired to the car by the dealer/salesman. you could also try a new battery or borrow the batt from the other fob. sometimes they just go bad. I recently had to replace an intermittent one for our 03 OBW. I was lucky and got one free but, i think you can get them off ebay.

check the axle nut? even though they are OEM, might be an axle - swap sides and see if the problem moves to the driver's side?