05 2.7 5 speed rattle

So for the past month of driving, I've been getting a funny rattle while driving. The truck is a 2005 2.7 tacoma with a 5 speed. Anyways, I get the rattle only while moving at 2000-2500rpm and when I let off the throttle to slow down or shift. I can't duplicate the sound while sitting still at any rpm. If I press the clutch and try to keep it at that RPM while it's rattling, it tries to go away but sometimes I can keep it going. A few months ago my power steering pump had a squeal and i had the throw out bearing squeak as well, but both of those seem to have gone completely. There isnt any play in my power steering pump but the idler pully has a little bit. I pulled the belt off and drove up the road and back and still have the rattle. Doesnt appear to be any loose body work and my CV's don't seem to have any play either. Any ideas? Right now i'm eaither keeping the RPM lower or higher than that 500rpm window and it doesnt have the rattle at the 60mph I normally cruise at. I'm going to try to find a videoscope and pull the valve cover off and inspect the guides, but I want to avoid changing the chain if at all possible, seeing as the FSM suggests pulling the engine.

edit: 150,000 ish miles
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no thoughts?