So I asked the shop He said rich condition was there by looking at LTFT/STFT.
Fast forward, he found P0304 was caused by a bad injectors. And Fuel pressure/Regulator were fine.
So used a reman 4 injectors and misfire is gone.
After coming home, I noticed LTFT was quite high at 14.
Today I changed engine oil and within about 3-4 miles of driving, it gave P0171. It happened around 2900rpm.
Coolant at 172, MAP 10.15psi, LTFT = 19, STFT= -0.78, 26.7mph
Load = 69%
Could PCV be the culprit? The PCV hose is also stiff. But shop found issue on IACV gasket – so they would have checked for leaks. Only reason I asked because of oil change.
Car runs fine – no hesitation even with the code.
Any advice?