A lot of the newer throttle controls are designed to do this if not properly adjusted. You have to set it to when the throttle is in wide open position the throttle lever on the engine is all the as far as it will go. The throttle control has a detent that it rest in and will not creep back and run slower. It is designed like this so people will run it at wop the way the engine is designed to run. Had an issue with a Dixie Chopper and the customer wanted it to stay where he put it. I called Chopper and this is what they told me. This did not satisfy the customer so I had to take it apart and put a bolt and a lock nut to tighten it down so it would stay where it was put.