My bike has developed a stumble coming on at about 5500 and clearing by 8000rpm. It runs fine at idle and revs out fine from 8k to redline. I tried pulling the fuse out of the power commander, but it didn't make a difference. My bike already has iridium plugs and the simplified fuel lines with a new filter in the tank about 4k miles ago. It ran fine until recently and the stumble seems to be the only problem. Before I start throwing parts at it is the anything that might cause a 100% repeatable predictable misfire at a specific rpm only? I am about due for a valve check and maybe a throttle balance but this seems like a fuel or ignition problem as the misfire returns on decel, and there is a lot of popping which it never did before.