Engine Idles Fast
WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition switch to OFF, then back to ON position. Using scan tool, select TP V and TPREL PIDs from PID/DATA MONITOR & RECORD menu. Observe TP V and TPREL PIDs while wiggling TP sensor circuits. At vehicle start, TPREL PID value will begin at about 1.25 volts and count down to the lowest TP V value read since engine start-up. If TP V value goes below normal range, then increases again, TPREL will set to the lower voltage. If TP V is about .04 volt more than TPREL value at closed throttle, PCM will go into part throttle mode. Check for loose or worn throttle plates. If no concern is found, go to TEST Z: INTERMITTENT , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article and check for intermittent faults.