Have a 2006 gp with 3.8 series 3 125,000 miles and i get a p303 code when i get the rpms up to 5000 and it never misfires untill i hit 5000. i have replaced the wires, coils, spark plugs, and switched the injectors around nothing changed it the light still flashes when i get to 5000 rpms also today when i came to stop and went to take off it got a p300 code. any help thanks.