Idle Air Control (IAC) Solenoid
WARNING: This page is about a different car, the 1995 Ford Bronco. However, it is still accessible from the selected car via links, so may be relevant.
IAC solenoid is an electromechanical device controlled by the Powertrain Control Module (PCM). The IAC solenoid is mounted on the throttle body and allows air to by-pass the throttle plate. The amount of air allowed to by-pass the throttle plate is determined by PCM and controlled by a duty signal.