I've been having intermittent loss of power and check engine light, code P2509, only happens when it's cold out and when I hit a bump. the first time the grid heater light flashed for a second when the check engine light came on. I checked and tightened all the grounds I could find including the grid heater. the 10MM nut on the ECM ground and the ground stud are badly rusted. it looks like the stud is replaceable, correct? anyone have a part number?