Differential Pressure Feedback Electronic (DPFE) Sensor
WARNING: This page is about a different car, the 1994 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Faults in DPFE sensor or circuit should set a trouble code. If no trouble code has been set, see CIRCUIT TEST DL in TESTS W/CODES article in the ENGINE PERFORMANCE section.