Differential Pressure Feedback EGR (DPFE) Sensor
WARNING: This page is about a different car, the 1994 Mercury Sable, 1994 Mercury Cougar, 1994 Lincoln Continental, 1994 Ford Thunderbird, and 1994 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
DPFE sensor monitors exhaust system and generates a varying electrical signal proportionate to exhaust pressure. This signal is sent to the PCM where it is translated and used to compute correct EGR flow.