Ell as the title says I have a 2009 nightster with 6500 miles. It has screamin eagle slip ons with cycle shack baffles and xied's. I've tested the xied with a dvom and they shot good. The bike surges in 1st 2nd and 3rd and when I'm around the 3500 rpm range it intermittently backfires at a steady cruise. I've checked for exhaust leaked and there are none. I sprayed a wd40 type of lube by the intake manifold gaskets and they seem to be fine. The only thing I found was that the gray/purple wire under the seat (throttle position sensor) was chaffed to bare wire and touching the frame. I patched it up with heat shrink tuning and shot the wire with a dvom to make sure it wasn't broken somewhere in there and it shot fine as well. It's really starting to drive me crazy. Anyone have any ideas on what else could be wrong? Do you think the throttle position sensorr wire grounding itself out could have feted the sensor?

I'd suspect a leak on the intake side, plugs or plug wires, bad elect connection or battery is failing.

Battery is new and gets put on the tender every night when I get home. Plugs don't looks bad but I don't know about the wires. They look fine on the plug side. I may get some starting fluid and spray it by the intake to see if there's a leak. I sprayed DuPont Teflon chain lube by the intake gaskets to see if it changes the sound. I read wd40 would make it sound different if there was a leak so I figured the DuPont lube would do the same.

Bump for ideas?

one other thought have you made sure there is no water in fuel.
surging backfiring is really associated with a lean condition

I really doubt there's any water in the fuel. I ride it every day and it's parked in the garage. I've only been caught in 2 rain storms in the past 2 months. I figured the xied's would help with a lean condition but I've rode with them on and off and the bike seems to run the same. I may send them in to have them tested even though they checked good for me. Maybe I missed something In the process

Hey man, get it up to around the RPM range that you feel it surging at and then spray some brake cleaner at the intake junctions. Also sometimes its possible to get bad fuel. Maybe drain your tank and start anew.