high idle at start then dips

It's called high idle. Supposed to do that until the engine warms up. If it keeps up, you have something adjusted improperly.

Ok, I just rebuilt a motor and everything from the ground up on this car. I've been building street rods for over 20 years, duhhhh, I know what its called and that a car needs to warm up. The engine is hot, I turn it off and then back on and the idel is high. So can someone who really knows something answer my question, please!!!

Only 20 years? I was in high school back then, rebuilding motors and whole cars, like my 69 Camaro. If the idle isn't coming down properly, something in the throttle linkage is probably adjusted incorrectly, like I said. Checked for vacuum leaks? Verified proper timing? Proper fuel pressure and delivery?

Unless you're perfect and never make mistakes, anything is possible. If you're perfect and never make mistakes, then maybe you were sold bad parts.

Just to add to this one how high is the Idle?Have you checked for codes?Or vaccuum leaks?A vaccuum leak on a fuel injected car will cause a high idle if its big enough.

Why would an AIC be running if the car is off?

AIC?

Oppss, IAC Valve LOL. But I went out to run it again and it ran just fine! Didn't notice I left the IAC unplugged. Seems to be an issue with the IAC, but its new and doing the same thing as the old one, clicking all the time even with the car is off. Could it be a short in the system?

Could be a short do you have any codes in the computer?

I'll look into the codes tomorrow, too dark now :(

Alright keep me posted.

Ok, I still need to get the codes from computer. But as a test I closed off the IAC port and unplugged the IAC Valve. Car runs fine! When I plug it back in the IAC Valve opens all the way and stays open, letting too much air into the intake. I'm thinking a short in the computer to the IAC Valve is sending power all the time to the IAC Valve, even when the car is off. If I reset the Copmuter could that help? To say the car was in bad shape when I got it would be an understatment.

What size engine do you have so i can get the correct wire diagram for the iac?

Heres the wire diagram we need to see if there are any codes in the computer.

Here is the trouble tree for the iac.

The Engine is a 1.6
I checked and there is no vacuum leaks. If I close the IAC all the way it will idle and run normal. If I plug in the IAC it will open all the way with the RPMs running up to 2000+ and keep running that high no matter how hot the car gets. The IAC makes a Clicking Sound all the time, even with the car off. But if I reset the computer it will stop, until I try to run the car again. Then clicking comes back and keeps clicking even when the car is off. I'm thinking a bad ECM?

Have you went thru the iac diagnoses i posted to rule out other issues besides the ecm?