Car Accelerates On Its Own problems of the 1998 Chevrolet S10

While my wife was driving along at approximately. 40 mph, the truck began to accelerate rapidly. Applying the brakes seemed to have minimal effect as the power of the engine seemed to overpower the braking. At that point she tried to shift the truck into neutral, but put it into reverse instead. This caused the rear wheels to lock, the truck then spun out of control and turned over upon striking the curb.