What causes my LTFT to be at +10.8, I drive for half hour, shut engine off, 30 minutes later I start the engine and the LTFT is now +14.1 and stays there while driving another half an hour? STFT varies +/-4%. According to my scan tool, the MAF (4.5 g/s) appears to be working properly. I haven't been able to find a vacuum leak. Fuel pressure is at 40 PSI. Stock 2002 Mustang GT. Injectors never have been changed. No codes. Car drives fine otherwise. Someone mentioned that it could be intake...

LTFT question - 2002 Mustang GT