EGR Valve
WARNING: This page is about a different car, the 1995 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
EGR valve is vacuum operated. The EGR valve is operated by a vacuum signal from EVR solenoid. Valve should be closed at 1.6 in. Hg and fully open at 4.5 in. Hg.