I'm having a problem with my 149 while mowing on level and relatively smooth ground. The tractor speeds up markedly and can be scary. It is like you suddenly bumped the throttle forward, but didn't do it yourself! I had a problem with the wear in the part that controls the speeding up and slowing down while on hills and fixed that by resizing that part. This is different I think. Anybody have suggestions as to what it might be and what to do? Thanks