This car still driving me crazy. I wrote here before about getting the code P0171 and some suggested a vacuum or exhaust leak. I sprayed some flammable connector cleaner around the intake manifold, throttle and PCV valave area with no noticeable change. I also added the Techron fuel system cleaner but still no change. I started tracking the fuel trims behavior for a while and i noticed that the lowest fuel trims ( Closest to zero ) was achieved only around 1200-1500 RPMs. For example long fuel trim sets around positive 15.6% while idling then drops to 7% around 1300 RPM then it will climb to 14% around 2000 RPM. I know that higher fuel trims at idle suggests vacuum or exhaust leak but would think that fuel trims will always go lower with higher RPM but not in my case as the fuel trims dip around 1200-1500 RPM then they start to climb around 2000 RPM. Is it fuel delivery issue or extra air issue?
Thanks!