Rough idle at start

[supertuner19]

Ok i have a 1997 ford explorer with a 4.0ohv engine i just replaced the upper plenum gasket and now it has a rough idle under 1000rpm it is like it has a leak somewhere but once you drive it runs fine it is only on the start up if anyone could please give some info i would really appreciate it

 

[supertuner19]

anyone have any ideas?

 

[jlsparky7]

Check for exhaust leaks. The leaks can seal up when the engine gets hot due to expansion.

A godo way to check for exhaust leaks is to run some seafoam. I have a how to in the link in my signature.

 

[jlsparky7]

Wouldnt hurt to clean the IAC, MAF, and throttle body as well.

 

[supertuner19]

Thanks for the reply i just did seafoam today seemed to help out alot i cleaned the iac too it seemed to help alot so i will see how it goes. It seemed like when i was driving too and let off the gas the idle surged which made me think it was the iac so i cleaned havent driven it since cleaning everything so thanks again!

 

[jlsparky7]

Great, glad everything helped.

Might want to try doing seafoam 1 or 2 more times just to be sure the engine is clean. Give it a tank of fuel or so before you do it again though.