Random High Idling Issues???

[TnTahoe]

For some reason my truck idles high at random times and I have no idea what is causing this. It idles high and sounds like a big fan blowing. So if anyone has any ideas to what is causing this let me know.

 

[TnTahoe]

anyone??

 

[sampsonr]

it could be the ac compressor... even if your ac isn't on, these trucks keep it cycling, this could what is making your engine rev up, when the compressor kicks on. Is is at random times or is when you first start it up??

 

[TnTahoe]

when i first start it up

 

[ChazMan]

when i first start it up

That's the clue right there.
When you first start up everything is cold, including trans oil. Next time when it happens, watch your rpm and the speed reading. Your rpm is probably higher than what it should be at that speed. The tranny is not shifting up and keeps the engine rpm high until the temp goes up little. I bet that doesn't happen on already warm/hot engine.