OK this is a 95 Grand Marq with a 4.6L 2v the engine would stall when you let your foot off the gas. So I told my nephew that it was his IAC he thought I was joking around with him I told him again after he replaced the o2 sensors and there was no change so I told him again change the IAC and he looked at me and said sure unlce I'll go right out and get a ID10T. I told him I'm not joke you need to replace the IAC I explained it idle air control and I showed him where it was in his car. So here is some if about the IAC.
Description and Operation
The Idle Air Control (IAC) valve controls engine idle speed.
The idle air control valve allows air to bypass the throttle plate. The amount of air allowed to bypass is determined by the Powertrain Control Module (PCM) and is controlled by a duty cycle signal.
Disconnect battery ground cable. NOTE : When the battery has been disconnected or reconnected, some abnormal drive symptoms may occur while the Powertrain Control Module (PCM) relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 miles) or more to relearn the strategy.
Disconnect the fuel charging wiring from the idle air control valve.
Remove the two idle air control valve retaining bolts.
Remove the idle air control valve and gasket.
Clean idle air control valve gasket mating surfaces. NOTE: If scraping is necessary, do not damage the idle air control valve gasket surfaces or drop gasket material into throttle body or throttle body adapter (depending upon application).
To install idle air control valve, reverse Removal procedure. Tighten retaining bolts to 8-12 Nm (71-106 lb in).
CAUTION: Do not use Carburetor Tune-Up Cleaner or any other type of solvent or damage to the valve internal components may result.
The Idle Air Control (IAC) valve cannot be cleaned. The idle air control valve must be replaced.