I have a 99 1500 5.2 automatic that has been experiencing a high idle when it’s cooler out (I live in Florida so it’s never cool or cold). when it rains (like today) it cold starts and holds an extremely high idle, around 2k. It was about 90 degrees so it’s not like it needs to choke or anything. When the engine warms up, it either doesn’t throttle down all the way and lingers around 900 or 1000, or has a shaky idle, not quite turning off but just not stable and smooth. My theory is idle air control valve but I don’t know enough about these engines to know for sure and just want some more people’s input!

 

Usually high idle is an air leak.

 

what could be an intermittent high idle, it’s not consistent by any means other than the outside air temp. Doesn’t even really have to do with engine temp

 

Expansion/contraction of gaskets/metal.

 

Pcv valve leaking?

 

Sticky throttle body?

 

I didn’t even know these motors had a valve for PCV, I just have a filter on the crank breather but this problem started well after putting the filter on. Where is the PCV valve?

 

that was my theory too for a bit but it doesn’t stick at open throttle positions, and it clings to one rpm