Hey, have you checked your timing? You can get backfire from your timing being off...and that can throw the CEL, giving you a "knock sensor" code...at least that's what I got.

Key to the timing getting done right is getting that TPS thing down...which I'm in the process of doing. When I took the throttle body off to do the TPS adjust, man was it caked with soot and crap. I cleaned that sucker spotless. Can't wait to see if it helped.