1 Lucky Texan

Dead battery in fob won't strand you, you get in (alarm honking) and use the ignition key to quickly cycle the ignition from off to on 3 times, that disables the alarm. Then , of course, you drive to the store and buy a battery for the fob, or you will be doing the procedure again.

Valvoline MaxLife is a good value. Did the Canadian '06 get the 5 speed trans?, that would need OEM or Idemitsu I think - especially in cold weather???? I may be confused when the spec changed and which trans.....

any dents in the trans pan?

maybe some breather and PCV hoses have been misrouted?

Immediately (before 2-3 drive cycles) after a battery disconnect 'reset', the ECU uses the factory base map in firmware to run the car. If the car's symptoms get better after a reset, that may point to a bad signal from a sensor. If it doesn't get better, might something physical like a dropped valve guide or ???

just chiming in to confirm....fluid level checked while idling correct? id the car new to you? any recent wrecks or work done before this problem began?

you can 'borrow' a coolant pressurizing kit from a parts store. That will help you visualize leaks without risking a burn. If it is a minor dripping on a hard-to-replace part, you cod use some Subaru Coolant Conditioner (ONE bottle only, installed ONLY as directred) and stop or prevent minor leaks.

did any ground connections get re-connected with the VC cover r&r ? vacuum lines re-seated? along with what GD suggests, next time it's misfiring/stumbling at idel, squirt some starting fluid/brake cleaner in the intake. If it smooths-out, maybe that points to a fueling problem? is system voltage OK at idle?

maybe the copper stuff helps ameliorate NOT properly prepping the heads' surface texture?

check the vacuum line on the fuel pressure regulator for wetness/fuel. maybe try a throttle body cleaning? like the SeaFoam with the curved nozzle gadget. check the knock sensor for cracks. can you get live data or freeze-frame data? what are the fuel trims? ignition timing/knock events?

paging @lmdew got parts?

not sure on newer cars but, oil pressure switches are not a common failure, but anything CAN fail.... At least, even on older cars, no worse than other brands... I'd just let the dealer examine things,they can hook into the oi lpassage somewhere and check actual pressure, inspect wiring and ground connections(which have been vital since the mid-90s with all the computerized parts), etc.

sorry to hear of your fire, hope everything gets taken care of smoothly.

https://japanesenostalgiccar.com/miyagi-subaru-ff-1-wagon-restoration/

lol, one of the first cars I drove regularly had a sticking throttle, being a dumb teen, I took to driving barefooted so I could use 'toe grip' when need to pull the pedal back up. When my sister told my Dad, he just came out and lubed the linkage to fix it. ah...good times, good times...

pretend there is an egg, that must not be broken, between the top of the gas pedal and the bottom of your right shoe.

weird

many possibilities for a 20 year-old car to have several areas needing attention. If someone saw a pulley wobble, which one? Or, did they mean the crank pulley is separating? stuck brake caliper, bad lower control arm bushing, worn tie rods,...etc.You need to find a Subaru-friendly shop and have them check it out. also, when was the last timing belt system service? I know miles are low, but the schedule also says 105 MONTHS.

what is your budget for this? It's not gonna be easy or cheap.

won't do anything unless you want more underhood sound/noise.

final drive ratio of rear diff must match the trans FD ratio.

any idler that wobbles 'needs' to be replaced asap any idler that spins like a skate wheel 'should' be replaced soon.

is it new to you? was it running and then quit? more details please.

I always adjusted with the star wheels. Works fine. Direction for tightening is embossed on the dust shield. I THINK upwards (yes, on bith side) is tighter. chock front wheels very securely, put trans in neutral, lift rear of car onto jackstands both sides, pull p-brake handle up to first click, adjust star wheels until you can't turn the tires (or, not without a lot of effort) - check, repeat if required but, always worked for me.

kinda seems like 2 different issues but, perhaps some coolant is shorting-out the high voltage? maybe spray the coil and wires and spark plug tube holes with wd-40, it can displace water.