G-day Micky and Norm, recently replaced a muffler on a Powertorque alloy base from about 1987 I found recently and it cured it's overevving at the same time, though throttle modulation could be better. It can't be made to rev low. It's either medium high or full throttle. I'm grateful it otherwise works well. Maybe check the muffler. The one I removed had a hairline crack all around the entry port of the muffler.
