2008 PETERBILT 386 Engine And Engine Cooling Problems

2008 PETERBILT 386 ROAD TRACTOR WITH A CUMMINS ISX 550 HP ENGINE. PURCHASED 9-10-07. ELECTRICAL ISSUES. THE DOOR LOCKS WERE BLOWING FUSES, THE GPS AND RADIO WOULD GO OFF AND ON, THE POWER WINDOWS AND WINDSHIELD WIPERS STOPPED WORKING, THE DASH LIGHTS AND BUZZERS WOULD FLASH AND ALARM WHEN ON ROUGH ROADS, THE LOW COOLANT LIGHT STAYING ON. SOME SENSORS;FUSES REPLACED. IN JANUARY HAVING OIL PRESSURE ISSUES. PRESSURE WOULD DROP TO 0 AND TRUCK WOULD SHUT OFF. TOLD THIS A CLOGGED OIL FILTER. CHANGED THE FILTER. CONTINUED TO HAVE THE PROBLEM. IN FEBRUARY WE TOOK THE IT IN FOR THIS, AND THE ELECTRICAL; THEY COULD FOUND NOTHING. WE PICKED IT UP, DROVE ABOUT 3 MILES AND THE OIL PRESSURE BEGAN TO FLUCTUATE. TOOK IT BACK, IT WAS KEPT SEVERAL DAYS AND THEY STILL FOUND NOTHING. THEN THE FUEL WAS NOT EQUALIZING BETWEEN TANKS AND THE TRUCK WOULD RUN OUT OF...