4.2 misfire / miss / spark knock when warm
I've got a 99 4.2 throwing a code of P0303 (#3 misfire). This things runs fine until warmed up, then misses at light throttle. Under moderate/heavy acceleration it runs fine. I've changed plugs, plug wires, coil pack, and coolant temp sensor to no avail.
During troubleshooting I stubled upon something -- When I disconnected the temp sensor (at back of driver's side head) the miss went away and the truck ran beautifully. I suppose this made the ECM think the engine is cold. This has to be a significant discovery, but I'm not sure what it means. I can rule out mechanical issues? I'm looking to the EGR system next. Has anyone had similar issues? What fixed it?