It's true that there are several sources for high idle issues.
If you are experience surging, it may come down to what I experienced.
My bike would idle fine, but would stumble at various engine RPM's.
i.e. if I held a 1600 RPM it would surge, but not at 2000 RPM; surging at 2300 RPM but not at any higher RPM.
The tech. removed my stepper and did some testing (don't know exactly what kind of testing) and replaced with a new stepper.
No stumbling since.
Cheers,
Chris