Ford Repair: 1994 mustang 3.8 ltr. engine, upper intake manifold, air control valve

Question
i've replaced the plugs wires and coil pack for my 1994 ford mustang 3.8 ltr v6. the problem is that after start up it seems to want to stall out and die, also it makes a high pith whistling sound (this started after i replaced air filter and PCV) any advice as to what's going on??

Thanks,

Todd

Answer
When starting the engine and at idle, the throttle plate is closed and the only air entering the engine is through the Idle Air Control Valve (IAC). This is all controlled by the Powertrain Contol Module. It uses the IAC to allow a small amount of air to enter the engine for starting and to adjust idle speed. The IAC is mounted to the upper intake manifold with two small bolts, and has a small electrical connector on it. It is about two by four inches. It may be sticking closed. You could try tapping on it with a screwdriver handle to free it up, or you can remove it (be careful, it may have a paper gasket) and clean it out with an Air Intake Cleaner. If this doesn't help, it may have failed and need replacing.  The high-pitched whistling noise is something resonating, it could be coming from a loose air box or lid, the intake tube, or the IAC. It could also be the wrong PCV Valve

I hope this helps,
Dave