WHILE STOPPED IN A LEFT TURN LANE AT A MAJOR CITY INTERSECTION BEHIND A LINE OF ABOUT 6 STOPPED CARS, THE ENGINE SUDDENLY BEGAN TO RACE AT HIGH SPEED. THE CAR MOVED FORWARD AND HIT THE REAR OF THE CAR IN FRONT BEFORE I COULD DEPRESS THE BRAKE HARD. I DID THAT, PUT THE CAR INTO NEUTRAL, APPLIED THE EMERGENCY BRAKE, AND TURNED THE ENGINE OFF AT THE IGNITION KEY BEFORE CHECKING ON THE CONDITION OF THE FOLKS IN THE CAR IN FRONT. THERE WAS NO WAY THAT I COULD HAVE MISTAKEN WHICH PEDAL WAS WHICH, AS I WAS ALREADY DEPRESSING THE BRAKE PEDAL TO KEEP FROM MOVING.