Just as the title says, my 01 busa is really jerky around 3.5-4.5 RPMs. At first I thought it could be a transmission. Then, well maybe its my clutch. I don't really have any clue what it could be. I've been told maybe its even the ECU but I'm not sure. I do know that I didn't have that problem before I had the piston rings swapped at my local shop but IDT that is it.