I, also, have a 2008 Road King Classic.
Do you get a check engine light when this happens?
On mine, I DO get a light, and it goes into "limp mode", where the power is VERY restricted.
Turns out (in my case) there's a service bulletin about corrosion on the plug connector where the wiring goes into the throttle body.
On mine, I disconnect/reconnect about 3 times, and that seems to remove (by scrapping) the corrosion, and all is good again.
