2004 Chevy Trailblazer LS – Rough Idle (Occasionally Stalls)

Please read before Commenting. No, it’s not the throttle body.

Problem I’ve had for a few years now and has been making me pull my hair out trying to fix it.
When the car is idling and AC is on (and especially after the engine has warmed up), the car will start to run rough, and occasionally the rpm’s will drop from it’s normal idle at 600 down to somewhere around 200-400, and once in a while it will stall. Whenever it does stall out on me, it will always start right back up.

I’ve never had a single f*@king code popup. The closest is every now and then the check engine light will flash on for a split second, but I can never get any codes from it.

These are all of the repairs that have been made to my car in the last few years. Not all of them are from me trying to fix this, but I’ll go ahead and share them all.

• Oil & filter and airfilter have been changed regularly
• Removed and cleaned throttle body (removed it again later to check make sure)
• Replaced gasket between throttle body and intake manifold
• Finally said f*@k it and replace the throttle body altogether with a brand new one.
• Replace MAP and Air Intake Temperature sensor.
• Replaced engine mounts
• Replaced AC relay
• Replaced spark plugs
• upgraded PCM firmware (done by mechanic)
• Replace variable timing solenoid
• Replaced battery
• Replaced fuel filter
• Replaced Camshaft position sensor
• Replaced up & downstream O2 sensors
• Patched a few small holes a few inches before the downstream O2 sensor

One thing I did notice is that the drive belt tensionser wobbles a small but noticeable amount. Can’t find anywhere online indicating how much is too much, so I think I might replace that next just in case.
My biggest fear is that it’ll be the ac compressor, but the ac always worked fine for me.

Any help/suggestions would be very much appreciated.