With AC off, it idles well at 500 rpms in gear.
If I turn on the AC, at times the RPMs will drop to 250rpms, studder, then rev back to 500rpms. It will do this continuously at a light every 45-60 seconds approx.
Any ideas on what would cause this? I did not notice any vacuum lines disconnected and tried to hunt for any weird noises with a hose and could not find any.