I have a MT2 that I broke in just as the handbook stated. The truck ran fine and I was in the process of leaning the engine when I had some gear problems. I changed the gears and now about half throttle, the truck takes off and I can't control it. My street has sloped curbs or the truck would be runined. It hits the curb, cartwheels into a yard and when it lands, I can drive off the lawn. The truck is fine until about half throttle. I changed all of the batteries and have the same problem. Any ideas?