Idle Control System
WARNING: This page is about a different car, the 1995 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
Faults in idle control system or circuit should set a diagnostic trouble code. See QUICK TEST in the appropriate TESTS W/CODES - EEC-IV (3.8L SC) article. If diagnostic trouble code has not been set, see CIRCUIT TEST KE in the same article for testing.