VEHICLE WAS ALWAYS MAINTAINED CORRECTLY, WHILE DRIVING AT APPROXIMATELY 25-30 MILES PER HOUR, THERE WAS A SUDDEN POPPING NOISE, VEHICLE LOST POWER WHICH STARTLED THE DRIVER AND CAUSED THE VEHICLE TO CRASH OFF THE ROAD. VEHICLE WAS RETURNED TO THE ROAD AND BROUGHT TO A PARKING LOT. NEXT DAY THE VEHICLE WAS TOWED TO MECHANIC AND IT WAS DISCOVERED THAT THE SPARK PLUG WAS BLOWN FROM THE ALUMINUM HEAD. MECHANIC TAPPED THE HEAD AND OWNER WAS FORCED TO SPEND $600 DOLLARS, OR REPLACE ENTIRE HEAD FOR $3500. MINOR VEHICLE DAMAGE DUE TO ACCIDENT, IF THIS OCCURRED AT HIGHER SPEED UNKNOWN WHAT COULD HAVE HAPPENED. PREGNANT WOMAN IN THE VEHICLE WHO WAS EXTREMELY SCARED DUE TO NOISES AND EXHAUST BLOWING INTO CABIN OF 02 F150 V8. *NM