WAS TOWING A SMALLER PICK UP ON A CAR CARRIER APPROACHING A STOP LIGHT APROX 30 FEET IN FRONT OF ME AT ABOUT 40 MPH . A CAR IN THE LANE TO MY RIGHT PULLED INTO MY LANE & I APPLIED MY BREAKS A BIT HARDER NOW THAT I HAVE LESS ROOM TO STOP. MY TRUCK DID NOT SLOW DOWN ANY, I PUSHED THE BREAK PEDDLE TO THE FLOOR & STILL WASN'T SLOWING DOWN. I PUSHED THE EMERGENCY BRAKE TO THE FLOOR YET STILL COLLIDED WITH THE CAR IN FRONT OF ME, CAUSING SERIOUS DAMAGE TO BOTH VEHICLES. AFTER MY TRUCK WAS REPAIRED I PICKED IT UP AT 6PM ONE EVENING & THE NEXT MORNING CALLED BACK SAYING SOMETHING WAS SERIOUSLY WRONG WITH MY TRUCK. IT WAS RANDOMLY SLOWING DOWN & SPEEDING UP OUT OF MY CONTROL & HEARING A ODD NOISE FROM THE ENGINE AREA. 4 HOURS LATER I SLAMMED INTO ANOTHER CAR BECAUSE IT WOULD NOT SLOW DOWN & STOP.