RPM jumping when first start up

[mphillips3]

I have a 2002 Sport trac and about a month or so ago, after I start it, the tach jumps up and down, and it chugs something fierce when I put it into reverse (or drive for that matter) if I do not let it warm up first. After it is warm, it is fine. Has this happened to anyone else, or does anyone have any idea what it might be? Any info would be great!

 

[steventadams]

For a rough idle the best thing to do is start looking for a cracked/disconnected vacuum hose somewhere under the hood. I think I remember reading somewhere that the 2002 IAC is integrated somewhere else but I'm not sure so I'll let someone else jump in on that one. You can try cleaning the MAF sensor, that helps a lot. And if none of that works it might be time to start looking to the lower head gaskets, there was a TSB (0012m? maybe?) on those. They tend to act up when it gets cold out and I don't know if that was fixed by '02.

 

[rwenzing]

I'll second the Idle Air Controller. Prime suspect for too low idle, too high idle or idle fluctuation at cold start.

 

[mphillips3]

Thanks for the help! I will check out your suggestions!