I have a 91 f150 with the 5.0 and a 5speed 4x4 with maual hubs.. When you start the truck; the motor takes a nd minute to find idle and then it reves from 800-1500 rpms till resting on about 800. You can lightly tap the gas pedal and the rpms shoot up to 1500 and hold for a good while. While driving when you disengage the clutch to shift it revs up about 500rpms abouve what they were. (Yes, foot is completely off gas pedal) I have replaced the TPS, MAP, and EGR positioning sensor. The AIC sensor looks new. Just bought this truck 2 days ago. When I got it; it had a speratic idle and would bogg out at idle, plus what I mentioned here.