Engine Surging 2500-3000 rpm
I'm trying to figure out the cause of my engine surging that occurs between 2500 - 3000 rpm. It happens in neutral and in all gears, clutch lever in and out. It's fine below that RPM and above that RPM but anywhere in that range the RPMs raise and drop by 250 - 500 rpm. It's been going on for a while but didn't really bother me at first since I rarely spent time in that range. However, that RPM range happens to be where I'm at in stop-and-go traffic and parking lots and is very frustrating as the bike bucks like a bronco at those speeds.
* Valves adjusted at 20000 miles. Didn't notice anything then.
* Rear coil pack replaced - no change
* Both plug caps replaced - no change
* Spark plugs in great shape and fairly new (NGK iridium) - no change
* TPS adjusted, then replaced/adjusted, put back to stock/adjusted - no change
* Vacuum leak found in loose front throttle boot. Tightened boot and no more leaks detected with spray downs with electronic parts cleaner - bike ran smoother overall but no change to surging
* CPS replaced - no change
* Simple resistor TRE installed (was hoping maybe different timing would show a change in rpm) - no change
* Throttle bodies sync'd - no change
* Charging system is strong, supplemental ground wire installed, and green connector eliminated
The strange thing is that it's exactly in that 2500 - 3000 rpm range, nowhere else. Idles great and runs up to redline great. 2400 rpm and below is absolutely fine as is 3100 rpm and above.