This sounds pretty familiar. My 04 comp g chipped a piston, and the debris from the piston clogged the cat keeping it from going any faster than 3k rpms. Being that your oil is clean, your bearings are most likely fine. It's the piston that caused it. And depending on the size of the piston with expansion and contraction, that would cause it to either make noise or not.

That's what I'm putting my money on anyways.