Differential Pressure Feedback EGR (DPFE) Sensor
WARNING: This page is about a different car, the 1995 Ford Explorer and 1995 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.
Faults in DPFE circuit should set a diagnostic trouble code. See QUICK TEST in TESTS W/CODES - EEC-IV (4.0L) article. If diagnostic trouble code has not been set, see CIRCUIT TEST DL in TESTS W/CODES - EEC-IV (4.0L) article for testing.