My kholer command cv490 mower engine all of a sudden runs at max throttle and will not change even after I move the throttle lever down

Hi,
Kohler governor systems themselves rarely fail. What does fail and cause this is the throttle shaft in the carb. This is the shaft nearest the engine and you would be able to lift it if it is failed. The wise thing to do is replace the whole carb in this situation. The brass or steel disc that controls the throttle will also be resting in the intake area of the engine. Be sure to check beneath the intake valve for screws that fasten that disc to the shaft; sometimes they will be beaten and travel right through the engine.
Here is a link to the service manual:
http://www.asberry.net/files/TP-2339-D.pdf
Peace,
Clarke