1 Lucky Texan

have you tried the FWD fuse?

usually called a sandwich adapter I think? https://www.amazon.com/s?ie=UTF8&field-keywords=oil%20pressure%20sender%20adapter%20filter&index=blended&link_code=qs&sourceid=Mozilla-search&tag=mozilla-20

axles will sometimes cause vibration. you could post a new thread asking for a good soob-experienced mechanic near your city. Have a different opinion after a test drive of the car. it is imperative the tires all be the same size/brand/model and near each other in wear. any change in the tires before this began? any jerking/bucking when driving tight circles on dry pavement? maneuvering in parking lots?

what's wrong with the diff now?

rebuild heads - reassemble with TURBO gaskets? (have head surfaces prepped)

pretty sure you had some atypical oil usage - not every 2.2 is gonna do that under 'normal' circumstances. isn't there a seal on the oil return into the pan that can cause oil consumption problems? or maybe when the conversion was done, there was some confusion about breather/PCV hoses? CCR in Colorado might have some parts for you - or check LKQ and car-part.com for engines, maybe craigslist for someone parting-out a car. the frustration comes thru in your post, I just have generic suggestions....sorry

starting in 06, the 5 spds in the WRX had a little shorter shifter, and a better 1st gear synchro - maybe other improvements? that might be a good trans to put straight-cut gears in. consider lighter flywheel and lightweight crank pulley too - 4lbs of rotating mass = ~1hp. anyway - sounds like a fun project! way above my skills

some discussion of modified gearsets; http://ppgearbox.com.au/page.asp?parentid=2&parent2id=14&parent3id=26

if this progresses to an unrecoverable state - you might have a 'Plan B' where the original mount point is blocked-off (tig welded over?), and you can get an oil sender adapter to fit under the oil filter. Of course, splice in some wiring to re-position the sender down there.

you could put dogtooth gears in at 1 and 2 I think there are sometimes labels on TOP (convenient huh?) of the diffs that help differentiate them. might be some good info for you over at NASIOC too.

I am 61 I love my 06 WRX wagon 3142plateless by alckytxn, on Flickr

kinda seems like either the battery's post is intermittent in the case - or possibly you have a cable with a lot of corrosion under the insulation.

trans stick is on the right side near the firewall, down kinda low. when the steering feels odd - or there is some squealing from the pump - look inside the PS fluid tank for foam/bubbles.

CV joints definitely go bad regularly enough - but so do wheel bearings. any work done in the last few weeks? is the sound central or left or right? checked the trans fluid level? use an infrared thermometer and compare hub temps L to R after a highway run. If one side is consistently hotter - maybe a bearing?

uh - TWO tires? are your tires now all 4 the same size/brand/model and near each other in wear? they should be.

I think a potentiometer or a small resistor network can be used to kill the code too. Just something adjusted to send - what? ~0.7V back on the sensor wire?

it may have something to do with cylinder scavenging or 'yaw' vibration/oscillation or ????? flat 4 boxer engines eliminate one entire set of vibration harmonics that plague in-line 4s anyway so, I'm guessing they have a good reason. check the graphs on page 15 here; http://www.surrealmirage.com/subaru/files/SAE_boxer.pdf

the only theory I have read about it, was that the 2.5 open-deck jugs just 'move around' too much for th 'old style' HGs.

(I always wondered if anyone modded a soob engine into a 'big bang' motor - kinda doubt the crankshaft would last long.) I think this is how our engines fire;

find one with blown engine, build an engine for it with turbo (mls) gaskets. Be prepared for rod knock if you don't rebuild to the bottom end. Might get lucky and overheat was minimal.

Discount Tire will match (after tax and shipping calculations) Tire Rack prices. Look at some Kumho tires - good value.

check www.cars101.com for cabin air filter instructions across several mode/years I like have our vacuum cleaner with small nozzle attachment ready when I do ththat filter service, just to clean-up the area as best as I can reach.

have used it for that a few times - works well. It can work well to remove sticky adhesive residue from labels, etc. too. have to follow up with a household cleanser usually.

leakdown test might show leaking exhaust or intake valve. smurfsack - how many miles on the engine? a used engine from a wreck could be an option - might have 1/2 the mileage. LKQ or car-part.com ,not cheap, but an idea.....