Download 1999 Mercury Cougar Idle Air Control (IAC) Valve Repair Manual – Idle Air Control (IAC) Valve Removal 1. Disconnect the vacuum line from the exhaust gas recirculation valve. 2. Disconnect the idle air control (IAC) valve electrical connector. 3. Detach the wiring harness from the IAC valve stud. 4. Disconnect the vacuum supply lines from the upper intake manifold. 5. Remove the IAC valve. 6. Remove and discard the IAC valve gasket. Installation 1. NOTE: Install a new IAC valve gasket. To install, reverse the removal procedure.