Afternoon gentlemen.

When 5.2 is first started, my idle speed keeps randomly going up and own until it warms up. I had a similar problem a while back, but it was constant and turned out to be a fouled IAC. I pulled the TB, cleaned everything (including the IAC) and the problem was solved. Maybe I should have replaced the IAC and it's ucking fup again but only at warm up?

Ideas?

Thanks.

 

i had cold idle surging in cool weather, up/down from 1000-1500 rpm. i kept trying to make it an IAC problem and replaced it several times. sometimes a new one would act exactly the same, sometimes it would act better for a while, just to confuse me. new TPS fixed the problem.

 

i have a 99 1500 5.9L, and if i start my truck up when it's cold or just hasn't been run all day, and let it sit and idle, after about two minutes or so they idle drops down and gets really rough and acts like the truck wants to die...i feel like i have a carburetor again...but it's f. injected. if i let it keep idling it will eventually pull itself out and idle normal but when i hit the gas for the first time after its had it's rough idle it feels like it's loaded up. also if it gets to the rough idle/feeling like it wants to die, if i punch the gas it normally takes care of it....any ideas...i've heard possibly the plenum? i have replace the tps and the iac valve and that didn't change it.
thank you