Rotational chirp, not belt related??

[RayW]

So, I'm hoping this is a known issue with Boxsters. I bought mine with a chirping sound that I swore would have been the throw out bearing. I changed it, along with the clutch, pilot bearing, and the IMS as long as I was there. The IMS with 100K was still perfect... Anyway, I ruled out belt / pulley noises by disconnecting the belt and running the engine, the noise is still there. The car is quiet on a cold start up, the noise will start coming on after about 5-10 minutes running. The noise will also go away at around 1500-1800RPM. It is primarily there at idle. Does anyone have any thoughts as to which direction to go to figure this out?