I have my old motor laying around still. It was turbo'ed, and developed a loud ticking. Rather than trying to diagnose, I traded parts off the car for a used motor and just threw it in. Here's a vid of the noise it was making.
Never did figure it out or tear it down, but when we were swapping my intake manifold over to the new motor, one of the butterfly's was loose and laying inside the manifold, along with one of the 2 screws. The other screw is missing, so who knows where at inside there it is...