sorta OT 97' legacy outback. honeymoon over, carbon buildup on #4 exhaust valve... Options

[rhodyguy]

holding the valve open. car ran great, then like shit. FAST! posting this here as subby swaps are the rage and some of you might not know about this unknown, to me, common issue.

check engine light came on solid and quickly went to flashing. free scan at flaps showed an issue with cyl #4 and it could have been a plug, wire, coil pack, or something else. i didn't want to take the swap out one item at a time route and paid for further diagnosis. result was the guide hadn't started to fall but the seal has failed and carbon is holding the valve open with virtually no comp on #4. the fix is far beyond my subaru mechanical skills. recommended...pull engine, pull head (and all that goes with it). while they're in there do the timing belt, tensioner, water pump (i get this) but also do the drivers side head :headband:. this is going to be VERY expensive if i take this route. unjustifiably expensive which bugs me as it's a solid chassis and i like the car.

do any of the "chemical" tricks really work? sea foam or any of the other touted methods?

i do not want car payments or to buy ANOTHER used car. i'll go to a one daily driver household first and adjust life style accordingly. it's not really the money. well, a bit, but getting the dough together affects other aspects tax related and heath ins coverage $.