Mine is doing the same thing now. I have the PC5 and had it dyno tuned. Ran great for a few trips now it bogs down here and there and backfires.So my ltr has a cherry bomb, no air box, k&n filter with pre filter, full Yoshi RS5 exhaust, and it's not quite running right. I've never actually messed with the mapping before, but I'm sure it needs to be tuned. How would I go about doing this?