F150 TRUCK WAS STARTED AND GEAR SHIFTER PUT IN REVERSE. VEHICLE MOVED BACKWARDS. AND WAS STOPPED BECAUSE OF VEHICLE BEHIND TRUCK. GEAR SHIFTER WAS PLACED IN DRIVE AND VEHICLE MOVED FORWARD, GEAR SHIFTER WAS THEN PUT IN PARK. ENGINE WHIRRED AND AND VEHICLE SURGED FORWARD. VEHICLE WAS STOPPED BY BRAKES. GEAR SHIFTER WAS PUT IN REVERSE. VEHICLE DROVE BACKWARDS, GEAR SHIFTER WAS PLACED IN PARK. VEHICLE ENGINE ACCELERATED AND TRUCK STARTED TO JUMP AND ACCELERATE BACKWARDS AS THE DRIVER TRIED TO EXIT AND HIT PARKED VEHICLE BEHIND TRUCK. ONLY WAY TO STOP THE VIEHICLE WAS TO TURN ENGINE OFF AS IT WOULD NOT SHIFT INTO PARK EVEN THOUGH GEARSHIFTER WAS IN PARK POSITION THE SUDDEN ACCELERATION WAS NOT A PEDAL CONFUSION. BRAKE SKID MARKS WERE EVIDENT ON THE CONCRETE IN THE DRIVEWAY.