I just bought this car. Cel came on as I was driving it home. Spits codes po301 po303 po304. I've got a rough idle it hesitates sometimes and I get pretty frequent backfires between up shifts. And it doesn't feel like it has the power it should. I started by replacing plugs. CEl went off for a bit then came back on. Cleaned my Maf and changed airfilters. Same thing. Found exhaust leak between the exhaust pipe that bolts to the turbo. Replaced gasket and fixed that. Ran fuel injector cleaner. Same things. Cel goes off then comes back on. My buddy said that because its a random misfire and not consistent and because no smoke comes out the oil dipstick tube or fill point when running and my vacuums gauge doesn't flutter it's probly not vaulves/rings/compression/head gasket. My next move is coil packs and wires. Any other ideas?
Garret gt30r .82 ar turbo. Rotated assembly
Invidia down pipe and cat back exhaust
Trial external waste gate .40
Aps 50/50 blow off vaulve
850 cc top feed injectors
Waldoro 2551 fuel pump.
Please help me. Thanks