NHTSA Complaint #11163266 — 2007 PONTIAC GRAND PRIX

RANDOM MISFIRE CODE WON'T GO AWAY SINCE WEEKS AFTER PURCHASING MY VEHICLE WHICH WAS THEN UNDER WARRANTY. THE DEALERSHIP REPLACED THE CAR COMPUTER & IGNITION COIL MODULE, SPARK PLUGS AND THE CODE TEMPORARILY WENT AWAY GOOD ENOUGH TO PASS EMISSIONS. THEY ALSO PERFORMED THE KEY RECALL THE CODE KEEPS COMING & NO MECHANIC OR DEALERSHIP CAN TELL ME WHY BUT THEY KEEP TAKING MY MONEY FOR A TEMPORARY FIX.THE DEALERSHIP SAID I NEEDED A NEW CATALYTIC CONVERTER. I HAVE REPLACED 5 SENSORS, THE IGNITION COIL MODULE TWICE, THE CATALYTIC CONVERTER, ALL SIX FUEL INJECTORS, THE FUEL PUMP AND HAD 3 MAJOR TUNE UPS. TO DATE THE ENGINE LIGHT SHUTS OFF TEMPORARILY AND ALWAYS RETURNS WITH THE SAME TWO CODES P0300 & P0420. IT FLASHES OCCASIONALLY BUT STAYS STEADY MOST DAYS.NO WORK DONE IS TURNING THE ENGINE LIGHT OFF FOR GOOD.