Air Injection Diverter (AIRD) Valve
WARNING: This page is about a different car, the 1995 Ford RV Cutaway, 1995 Ford Econoline, 1995 Ford Cutaway, and 1995 Ford Club Wagon. However, it is still accessible from the selected car via links, so may be relevant.
AIRD valve is operated by vacuum and directs air pump output to exhaust manifold or downstream to catalytic converter, depending on system requirements, engine mode and control system.