The real surprise!
It was a real surprise to me to find out what needed to be done to fix this problem on my 2007. I have had throttle/idle speed problems since the day I got the bike. It only had 500 miles on it then. My son and I have tinkered, read and done everything that has been suggested on the boards and we not only had all of the problems described here, but it kept on getting WORSE!
Surprise!!!
The fix for me is related to the idle stepper motor. The nyloc nut on the shaft of the motor (beautifully located between the engine block and the stepper motor) failed and the nut backed itself off the shaft.
A little loc-tite, a few choice words trying to get it all back together after screwing the nut back on the shaft and the bike runs PERFECTLY!
I now have a fantastic bike. Even better than when I got it!