It was doing this before the distributor change. not as bad though. I doubt the carb has been rebuilt since it rolled off the assembly line. I am not sure if i should start messing with adjusting the carb or rebuild it. I have found a few threads about his same issue but havnt found any good answers. It only has this issue between idle and full throttle. once the peddal is past a certain point, you can push it down pretty good with no backfire.