Well, I did not have time to run a good test, but it looks like when my A/C kicks in, the idle goes up a liitle, just like it always did, and
when I disconnect IAC valve while idling the RPM goes up and then fluctuate above normal. This IMO means that IAC valve is working. But like you said, it could be an intermittent prob due to durty valve (why? K&N always cleaned properly) or faulty wire from IAC to PCM.
I will remedy my EGR problem first and then we will see