Q&A

 Master

It sounds like your car may have a dirty throttle body and/or a poorly functioning Idle Air Control Valve. When the car is first started cold ( and you live where it gets really cold ) the engine must idle faster, say 1500 rpm until the combustion chambers warm up. Once the engine is warmed up, it can idle much slower because combustion is then much more efficient. The fact that your car runs better when it is warmer and driving is more evidence that supports this thesis. How many miles are on your Ford? Have you or your mechanic ever checked the throttle body? It should be cleaned every 30K or so. Even though some Ford throttle bodies have a yellow sign that says that they can not be cleaned, this is due to the plastic parts in the Idle Air Control Valve. One can CAREFULLY wipe out the throttle body with a shop towel that has some throttle body cleaner on it ( and not have to spray anything in to the throttle body itself ) and really clean the throttle body.

After you replaced the IAC and cleaned the throttle body, you need to do an idle adaption reset. This involves, starting the car which may take several tries and holding your foot on the throttle until it runs. Then slowly take your foot off the throttle and let the engine idle for 3-4 minutes. Then, without moving the car, put it in drive and let it idle ( with your foot on the brake ) for another 3-4 minutes, then, while it is still in drive, turn on the A/C for 3-4 minutes and let it idle. Do this when it is already warm.
Do you ever get a Check Engine Light On? If so, having this code retrieved could really help. How is your maintenance i.e are you plugs etc fresh and of good quality. What type of IAC did you get. Ford's have very carefully calibrated IACs and need to have the calibration number checked and matched. If one is purchased from a generic parts store, it often will not perform correctly.

 Journeyman

Sounds like a problem with the intake gaskets/o-rings.The problem is more pronounced when it is cold out and the engine is stone cold,the o-ring gaskets are as hard as a rock and suck air passed them.

All of the following answers are correct and I would recommend changing your IAC as well your intake manifold O-rings for good measure. Also, be certain that you also replace the gasket on the IAC as well. And, yes it has a gasket!