I am having a random rough idle problem. The truck will idle fine for most of the time but randomly stumbles. It usually passes in under 30 seconds. The one time I have been under the hood when this happened there was a loud whistling sound while it was stumbling. This made me think of the IAC valve. It just threw a P0132 code (1/1 O2S Shorted To Voltage) however. So now I'm not sure if it's the IAC or an o2 sensor that's bad. What do you guys think?

 

the IAC whistle is likely just it opening up to maintain idle.
replace the front O2. shop on the internet for a NTK and before buying one, crawl under the truck and unplug the harness up on top of the trans. you might have to clip or pull loose the push in clamp that holds it to the chassis.

verify whether your plug is round or square.