Mike: The speed of the mower blades IS controlled by the speed of the engine - If the engine speed goes up and down, so will the speed of the blades. If you get the engine problem figured out, your blade problem will be OK. And the pedal DOES control your ground speed. Maybe you're going too fast to get a good cut on the grass - try slowing down (with the pedal - not the throttle) and see what happens.