I have a 02 WRX Wagon and everything is stock on the car. I scanned the car and it read P0301,P0302,P0303, and P0304. It is mis-firing on all four cylinders.
I replaced all four sparkplugs, and all four coil-packs, but still the light came back on. All four cylinder is still misfiring.
Should I change the MAF sensor? It look kind of dirty and I clean it a couple of time already. The engine doesn't said any thing about the MAF sensor, so I'm not sure about changing it.
At this point I don't know what to do any more, and the dealer is not really helping, they just start naming a bunch of things to replace.
I also checked my Alternator, and it read 13.93 volts, I know that it a little below normal, so I'm thinking about replacing that too, but still I don't know what really cause it. HELP!!!!!!!!!!!!!!!!!!!