The car in question is 99 Grand Prix GTP.
Half the time it will crank up and idle just fine, other times it will crank up, idle fine for 30 seconds and then idle surge for another 30 seconds or so. The surging is anywhere from 200-500 RPMs. Last night it did something completely new though. I drove the car for around an hour and this time it didn't idle surge until near the end of my ride when I came to a stop before getting home. It continued to idle surge until I got home and turned it off.
A few things I've noticed when it is idle surging:
The vacuum gauge reads around 11 in/hg (down from 15-16 in/hg)(It will go back to normal when surging stops)
The car seems to be sluggish when pushing on the gas
The surging is normally 200-500 RPMs
Sometimes the idle will raise to 1100 or so but continue to surge
Things I have tried so far to resolve it:
Junkyard MAF
Cleaning the TB and MAF
IAC is a year old so I haven't tried a new one.
Also, no codes are being thrown
