ON TWO PREVIOUS OCCASIONS THE ACCELERATOR STUCK - MID 1998 - ONE ON A FREEWAY ON RAMP AND THE OTHER WHILE ACCELERATION WHILE TRAVELING 65 MPH ON THE FREEWAY. I PUT THE VEHICLE INTO NEUTRAL AND TURNED OFF THE ENGINE WHEN STOPPED - IT WAS FINE UPON BEING RESTARTED. I TOOK IT INTO A SHOP BUT THEY WERE UNABLE TO FIND ANYTHING APPARENTLY WRONG. ON JULY 19,1999, WHILE TRAVELING 65 MPH ON THE FREEWAY, I BRIEFLY ACCELERATED. THE ACCELERATOR AGAIN STUCK. I TAPPED ON THE BRAKE TO CHECK IF THAT WOULD HELP. (I WAS NOT USING CRUISE CONTROL AND SELDOM USE IT.) THE VEHICLE CONTINUED TO ACCELERATE. I THEN PUT THE GEAR INTO NEUTRAL - IT WAS AN AUTOMATIC. THE WHEELS THEN FROZE/LOCKED WHICH CAUSED THE TRUCK TO SKID AND THEN ROLLOVER 1 1/2 TIMES. I DID NOT APPLY THE BRAKES HOWEVER THERE WERE SKID MARKS ON THE ROADWAY. THE TRUCK HAS BEEN WELL MAINTAINED AND OTHER THAN THIS PROBLEM FREE.