Okay, having read through this thread, arguments and tuning aside, I have the same problem and have done the same things on The Pilot's list. The only difference is that I'm running an APH exhaust but free-flow none the less. I have also gone back and forth with stock vs race eeprom. the problem always remains. I've also renewed inlet seals. Even got the standard ones to seal! Third attempt, anyway. My plugs, however, confirm that the rear cylinder is running a bit lean and the front is running rich. I've disabled the O2 sensor making changes by taking off open and closed loop learn and setting the max afv and ego corrections to 100. So, where now? would/ could a head gasket leak cause this intermittent fault and lean code? Any other ideas?
Thanks.