Hello! XB12S here with a K&N and Torquehammer (originally D&D) exhaust, but no other mods. I have the dreaded XB stumble up to about 4000 RPM, most noticeable in the 2000-3500 range and at part throttle. Cruising in the city and parking lot riding are no fun at all. Full throttle operation is great, and I hear occasional misfires at idle but without any other DDFI Buells around, I don't know if that part is abnormal or if it's supposed to have a skippy idle like a Harley. I have pored over many forum threads with solutions that have worked for others that have barely changed how mine behaves.

Any other diagnostic ideas or items I am forgetting? My next move is to get Megalogviewer HD and do some ECMDroid datalogging when the weather breaks. Thanks in advance for any help!

See below for what has been tried without a noticeable change in behavior.

-new intake seals
-many TPS resets
-Buell "race" tune
-new plugs
-new wires
-breather bypass
-subframe grounding points cleaned
-new ground braid
-redundant ground from subframe to coil bracket
-D&D-specific tune from Buelltooth
-Switch from D&D to Torquehammer exhaust (heard D&D is hard to tune for)
-Back to Buell "race" tune
-static timing adjustment

All sensors appear to behave normally in ECMDroid (i.e. IAT,CLT,TPS), and AFV is always within 10% of 100. There is no obvious wiring damage. I've eliminated the fuel pump as a suspect since it performs well at full throttle, but I could be wrong in that assessment. I may have forgotten a couple of items that I checked.