I was having an issue with rough idle and from what I found it appeared to be the IAC. To replace I partially removed the throttle body. Put it all back together started up and it immediately revs to 2k rpm's and there's a horrible whistle coming from the engine bay. Thinking vacuum leak but seems odd since nothing got touched. Any help would be appreciated. TIA

 

Most IAC replacements do not work or are not the solution. The IAC rarely actually goes 'bad'. Give the original a good cleaning with carb cleaner just don't push in or move the pintle, and also clean the throttle body too. Then put it all together and look into O2 sensors or injector cleaner.

 

The original iac fell apart when i took it out. I was able to determine that the whistling will stop when i hit the gas. So it's idling around 2k and whistles but stops whistling when i hit the gas pedal.

 

You have a vacuum leak. Quite likely the throttle body base gasket.

 

I took everything apart this morning and verified all gaskets are intact and mating surfaces are clean. Started up and idle seems to be coming down but whistling is still present. It immediately stops when i hit the gas pedal but immediately returns when i take my foot off the gas pedal.

 

See if you can figure out where the whistle is coming from. A piece of hose makes a good stethoscope for such an occasion.

 

I will a bit later. Too early to be waking the neighborhood. It's so loud that you really can't keep your head around it for too long. I'm almost wondering if something unrelated failed in between my replacing the iac. Gonna hit the service manual in a minute as well

 

I did a quick video this morning that might help further diagnose it. Almost seems something unrelated broke. Idk