Okay, I have a 94z28, auto tranny. It now has about 80K miles on it. Recently a problem has come up. Above about 4600 rpms, I've got no power. My engine sounds like a popcorn popper. So its either knocking or pulling timing, or something. I don't know what to do. The check engine light typically doesn't turn on during this either (however, it does intermittenly at stop lights, and has since I replaced my elbow). Anyways, I was just hoping for some advice, I really hope its not the opti!

Thanks