One day when I left work my car idled at 1300 for a few seconds and fell to what it normally idles at. Today when I left for school it idled around 1300 and now it's idling at 1400. I'm thinking it may be the IAC valve. I had a very similar problem in my 95 z28 and it turned out the IAC valve was bad. I took it off on my 3.4 and cleaned it but that didn't work. Anyway I can test the IAC to make sure it's bad? There's no check engine light on.
I also did spark plug wires recently and in the morning when I first start it up, it kind of feels like it's missing (But I don't think it is actually missing) when I accelerate but that goes away within a minute of driving. I don't know if that has anything to do with my issue.
Thanks in advance for any input.

 

Could be a bad IAC valve, but also a vacuum/air leak, or sticking throttle/cruise control linkage; make sure that the throttle valve returns to a fully closed position every time when there is no pressure on the gas pedal. You may also want to recheck the plug wires making sure they are connected tightly and not arching to ground.

 

I cleaned the IAC some more and I unhooked the negative battery cable for 30 seconds and it seems to be idling fine now. Time will tell if it is actually fixed or not.