GeneralDisorder

Correct, your car comes equipped with headlights from the factory. Good observation. GD

Yes. Subaru sells remans - get one from dealer parts. GD

Battery quality has gone WAY down in the past 10 years. Even AAA is telling people you can now only expect 3 years from the average new battery. Less for cheap ones. If you want quality it's available but the price is higher. You need an Odyssey 35-PC1400. Will run you about 3 bills now. But they have a 12-15 year design life and often outlast that. GD

Then install the complete 2.5. Don't use any of the 2.2 stuff. Waste of time.

Sounds like all the shops in town that end up towing the car to me when they can't figure out the problem. Yet another hack with "experience" that means nothing. Without a systematic, unbiased method, you'll just spin your wheels like that. Maybe it's not the injectors. But that's what the data points to. You go where the data takes you, not where you "believe" the problem to be. GD

Yeah Denso or Koyo is fine for the radiator. Just get the hoses from Subaru.

Chances are the HG's are ok. But the radiator is over 10 years old so replace it regardless. Also check for any obstructions in the condenser fins and between the condenser and radiator. Get new hoses FROM THE DEALER. They fit the best and aren't that expensive. GD

Change the radiator. If that doesn't help try that bypass trick. If it still does it, then you need new HG's. Sorry. GD

As a shop, I will typically not replace the EA axles if I can reboot them due to the extremely poor quality of Chinese aftermarket replacements. And for newer cars we get the remanufactured axles from the dealer or we get used ones. Occasionally we will reboot them also. For other-than-Subaru applications we will usually get aftermarket replacements though there are times (Nissan Juke Turbo comes to mind) where brand new OEM ($675) is the only option.

Experience with specifically Subaru doesn't really have much to do with this troubleshooting. The troubleshooting flow for the fuel delivery is going to be the same on a 2004 Subaru and on my 1986 Trans Am. Because both are MPFI. I would not approach it any differently. All I can say is that 35 years of experience is much too long to not know this. I would have that problem narrowed to the exact cause in under an hour. No start diag... I would check oil level (I always check oil level under the "do no harm" doctrine), and spark. Depending on how the engine sounds while cranking I would then go to either timing belt, or starter fluid test. From there we would find it idles on starter fluid. Commence testing fuel delivery. Pressure and volume good, injector signal good....pull injectors and flow bench. Done. GD

The filter would be inside the tank, above the pump, bolted to the pickup/sending unit bracketry. Or it's been deleted from under the hood. Which is a terrible idea.

Well you can just put rings on the old pistons. They will seal fine you will just continue to have piston slap is all. There aren't really any "updated" pistons - just new pistons with new skirt coating, which eventually wears off and then it goes back to slapping. I suppose maybe they changed the barrel design of the skirts.... problem is that skirt to wall clearance is probably somewhat larger than it was when the block was new, and unless these factory style pistons have pretty darn tight skirt to wall, or are heavily coated with teflon, they slap like a forged piston no matter what you do. When we knurl them we put them back in with zero skirt to wall clearance and just let them run themselves in. Gives the engine a slightly diesel sound to it if you are standing in front with the hood up. Basically inaudible from the cabin. The pistons are sized A, B, and C, and in order to get the specific sizes, the only source is the dealer - if you buy aftermarket they are all one size and will slap worse than what you have now (without knurling). Another option is to go to forged pistons, and the JE's we have been using for the last few years on our turbo builds are surprisingly quiet. They have a skirt coating also. They are a 2618 alloy. We never knurl the forged pistons - we just let them do their thing. If they slap - it's almost considered a badge of honor. Means you have forged pistons. The kids love that. And yes if you wanted to ship it, we could handle that for your also. A replacement short block.... well if you wanted that option I would just get a reman from the dealer. About $2k and comes with a 3yr/36k warranty. 0 miles..... GD

What year OBS?

That is the poster child for synthetic oil, and regularly replacing the PCV valve and cleaning or replacing the PCV to block hoses/fittings. Don't neglect to remove the separator plate on the back of the engine and clean that also. With new rings, and synthetic oil, this will basically become a non issue going forward. The pump size marking is visible without dissasembly. It's right above the timing cover on the passenger top corner. GD

I've see plenty of plugged exhaust cars, and they will start and idle usually. Loosen the header off the engine and see if that makes a difference. It's only 6 nuts. There should be a fuel filter under the hood unless it's actually a 2005 model in which case it's a canister in the tank above the pump. The car SHOULD have a fuel filter either above the pump or in the engine bay. If it doesn't then definitely start flow testing the injectors and get a filter on it. GD

Try starter fluid again. Sounds like possibly the injectors aren't firing or are plugged. Power and ground trigger is good, but you need amperage to turn on the injectors so do a voltage drop test. And of course the injectors need to flow fuel as well (and the filter too). I have seen filter elements blow out due to high differential pressure and clog injectors. GD

Try unplugging the MAP sensor and see if it will run in limp mode for you. Also - even though you have fuel pressure and injector power/signal - have you tried some starter fluid into the air filter housing to see if it will fire? GD

Yes you need to change the pickup to use the STI pan. The pump will say the size in the upper left hand corner on the outside. If it says 10 then just leave it be. If it's a 7 or a 9 then replace it with a 10. We never see the backing plate bolts back out on these, and we don't bother with the o-ring. Reason being there are three more of the same o-rings between the engine block case halves and since those aren't being replaced either...... we never see a problem with any of these o-rings anyway. They invariably look fine if you pull off the pump or split the case, etc. GD

The 99 to 05 are all roughly compatible. The difference are in the PCV fittings and are all easily worked around. The interchange will not show compatibility because of this but if you retain the intake and cam/crank sprockets for the car, the rest is straightforward and no problem at all really. GD

Perhaps too much heat was used and fried something. I have soldered a couple dozen of these and it's 100% success rate so far. Strange. GD

The newer one's like that you have to jack the engine out of the cradle. My guess is they didn't do this and instead tried to remove the 2/4 valve cover by taking the injector death shield off and in the process also moved the fuel rail and made the job WAY harder than it needed to be. Completely incompetent IMO. This whole job should take about 2 hours for an experienced tech. GD

Other than the misfire, that's probably all related to the transmission harness. You probably forgot a ground, or forgot to plug something in. Did you take pictures or film it along the way? GD

So you do know how to use YouTube. Look up how differentials work. There is nothing wrong with your car. GD

Not much published info out there. Most information you need is on this forum. What specs are you looking for? It's all in our heads for the most part. Find a factory service manual on ebay. GD

You need remedial training on differentials. And take the car in for an alignment. GD