Windstar rpms going up and down at idle

I have a 99 Ford Windstar and the RPM's will fluctuate from 1000 to 2000 when at idle and then shut off within a few seconds. This seems to only happen in the morning when its cold and only at idle, if I put it in park it seems to get better. I have gotten ripped off by mechanics before so I thought mabye someone could help me figure out what the problem is before I take the car in. I am a single mom and don't have the money to throw away espeshally before Christmas. If you someone could help thanks. :)

It sounds like the Idle air control valve.. Or "aka" IAC valve.. It can be removed and cleaned. Most of the time carbon builds up in it and the plunger has trouble moving freely.. It can cause the idle to jump around a bit when its cold. On mine I cleaned it a few times so if it keeps acting up I will replace it. But so far its ok.. Not a hard fix..