1 Lucky Texan

scan for codes. seems like a 'dark current' power drain to me. You could check the current draw, if high, start pulling fuses to try to pin-down the circuit responsible. does it have a replacementradio? check for stuck CD. Does it have an amplifier? make sure it turns off completely - double check any aftermarket electronics.

The front calipers must be able to slide - sticking calipers lead to big differences in outer vs inner wear.

coil is possible - due to waste spark system, the specific pairs 1&2, and 3&4,share coil halves. Doesn't mean somethingelse might not be going on..... find a youtube video on subaru rear brakes - most newer models have a small drum that has the parking brake shoes, surrounded by the disc part. Your car 'may' be old enough to have drum rear brakes. Someone else will chime in with better info I'm sure.

you don't have to buy from them but, Crutchfield.com has been in aftermarket car audio for decades, see what they have - nowadays, most HUs also have bluetooth.

Not sure anyone really has time/resources to do rigorous testing so, most advice is based on many, many anecdotal reports. There have been some that strongly maintained worn trans mounts were at fault....The HERI axles claim they do not vibrate, but their construction is different. many variables.

well, dang!

do you get the first honk? I have read in the past of people fixating on the number 10, evidently, you just keep flipping the key until you hear the honk - might end up beiing 11 or 14 or w'ever.....

so jealous.....

checking the fluid while idling, on level ground? (occasionally someone doesn't know that)

no reason to take a 17 year-old car to the dealer. Heck, probably none of the techs have worked on anything older than a 2010 - certainly not many.... look for a soob-friendly independent mech. good job getting a refund !

The dealer didn't retrieve any codes? coupla things that can be bad without throwing codes; knock sensor and engine temp sensor. Knock sensor can kill power by pulling the advance. Some folks report cheap ebay sensors working well. temp sensor can cause hard starting if NOT reporting a cold engine when cold, or, flooding/'choking' if always reporting a cold engine even when warm. does the car behave better immediately after a battery disconnect ecu 'reset'? If not, I'd expect you're looking for something kinda physical; vacuum leak, low fuel pressure, sticking valve, maybe intermittent ground somewhere,.....?

Has it done this across more than one tank of gas? is it associated with moist/dewy conditions?

when I was younger, I either never had a seized piston, or maybe once I paid someone to do that work on an Rambler??? not sure. thanx - are these washers all common sizes then and available over the parts counter? You have said in the past that I was basically driving a ticking time bomb and, pulling that screen for the turbo line, at least(I might skip the valve system ones), seems do-able. what size washer or do I pull it and take it to the parts store to match?

if I was able to find this on my turbo, would I just need a new washer after I remove the screen? I have literally never removed a banjo bolt - all my old-car experience was before they became common I guess.

I saw someone do the math once, 3 drain/fills gets you over 80% new fluid. There are a coupla methods I think to do a full fluid replacement but they are less DIY 'friendly' than just using the drain plug. I use Valvoline MaxLife in our 03.

the 4 primary things that will throw that code seem to be; a:f ratio off , exhaust leaks , bad rear O2 signal , bad cat. conv. I know some of those are very general, but start with confirming them if possible. The temp out the back of the converter should be about 100*F more than the temp going in.

no codes thrown? how old is the timing belt system parts? double-check cam/crank timing immediately. you might consider dropping the exhaust and looking for 'dropped' (shifted) valve guides.

If the present wires are other than original brand, yeah, NGK. otherwise, what those guys already said.

^^^^ good post

I recall reading about some lines made from a cupro-nickel alloy?

Dorman sells a box of 20mm washers but, yeah, you could just buy a several next time you're at the dealer too. https://www.amazon.com/gp/product/B001SNRGAA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

if a few sprays of starter fluid calm it down - that would point to fueling.

On my WRX I run Kumho ECSTA ASX or ECSTA 4x .

if the bearings for the toothed idler are failing, that could be a source for magnetic debris too.

fix the headgasket, sell the car, buy a turbo Forester to play with.