So my son’s 2008 WRX randomly threw a P0301 code (independent, no other codes). I did basic work, plugs with proper gap, a #1 coil pack, and cleaned MaF. The plug condition (all 4) was poor and I thought I had this. The car seems to start normally and idle semi-Ok, seems like there is still a minor miss. Cleared the codes and drove, it came back, power seems ok as RPMs pick up some small loss of power in low RPM, interestingly enough in driveway at idle it would go off and come back on when reving. Did a bunch of injector cleaner and a couple tanks of good fuel, still no change. Followed him on a highway drive today, he said it would stutter on uphill climbs, behind him there was a definite odor (smells really rich, emission smell), otherwise fuel mileage was down and car did not demonstrate poor driveability. The car has an intake, exhaust, and tune. Only about 85k on the clock. Hoping this is a common item that can be supported with minimal sarcasm . Thanks for the help!