Throttle Position Sensor
WARNING: This page is about a different car, the 2001 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Throttle Position (TP) sensor is a potentiometer mounted to engine throttle body. PCM receives a signal from TP sensor relaying throttle plate position. TP sensor failure will cause PCM to operate in fail-safe mode and raise line pressure to prevent transaxle damage. This condition will result in harsh engagements, firm shift feel, abnormal shift schedule and TCC not engaging or cycling.