I have spent a lot of time in the garage already trying to figure this out. Will someone who has been though the TPS problem before please point me in this right direction? Disconnecting the TPS significantly reduces a rough running condition at 1/8 to 1/2 throttle or so under light loads on my 09 YZ450F. The question is what to do about it. I prefer the feel of the motor with the TPS connected, but fixing it sounds like a major PITA. From what I have been reading, people approach the faulty TPS from a number of angles. Do I need to adjust the TPS, buy a new TPS, replace the CDI, or all of the above? Here are the resistance measurements I took last night: Resistance blue-black (static): 4,220 Ohms (within spec) Resistance black-yellow (dynamic): 500 closed, 3.66 open Ohms (not quite within spec). If this is a wild goose chase I'd rather just live with it. Thanks for any help on this one!!