2001 Dodge Grand Caravan ES idle problem

I have a 2001 Dodge Grand Caravan ES 3.8 liter engine. I'm having problems keeping the van running at cold starts. When I start it up, the RPMs go close to 1500 RPMs and then quickly drops down to 600 RPMs and lower. I have to give it a little gas to keep it up above 1000 RPMS just to keep it from dying. After about 30-45 seconds, it runs fine. As I stated above, it happens only at cold starts. Once the engine has been warmed up, I can shut it off and start it up again with no problem. My last mechanic checked it out and he said he couldn't find anything wrong. They said the throttle was gummed up and they cleaned it but it still does the same thing. Any ideas? There are no codes and no check engine light on the instrument panel.

possible vacuum leak, faulty iac. I would have your mechanic monitor the iac steps cold and hot..

Engine needs a rich mixture and advanced timing espesially on cold starts. The engine uses sensor inputs and fixed computer outputs to make that happen. You need a scanner with real time capability to determine what is happening. Outside chance the EGR system could be the culprit. May be worth checking.

One other thing to look at is the coolant temperature sensor, if the computer thinks the engine is warmer than it actually is, would cause that issue.