I have installed my air throttle and its working fine. Found old parts from army truck on E-bay. Air cylinder was bad but the bracket and heat shields was right for my Detroit Diesel 8V92. Also with it was a push rood extender for the air cylinder. These are the parts that are not available from Williams Controls.Now called Brake Systems inc (BSI). I have been looking for this equipment for over ten years,but have kept the original parts for a pattern and made two new mounting brackets with heat shields. One is installed on our bus and I have one set ready to help a fellow Busnut.
This is one big improvement over the old cable throttle and cable modulator. Seams the bus is a lot faster and shifts better up and down. This is the only bus that I have driven so I don't know how fast it should have been. I think it shifted to fast before going up the gears and that made the bus slower. The top end was fine just slow getting there.
Getting new tires in the morning for our summer travel in the North West.
Paul
I gather you also hooked up the air actuated throttle modulator. Properly working-should vary the shift points in relation to your gas pedal. Sounds like the throttle modulator was not hooked up or not adjusted correctly before. Good Luck, TomC