Where do I begin. Several things have been done to fix this car. No engine light. But when the car get up to highway speeds ( 60-70 mph) the car flutters and feels ready to cutoff but doesn't. O2 sensors, spark plugs, supercharger, egr valve, pcm computer, map sensor, maf sensor, all new vacuum hoses (could be the problem because the hoses are hard to put in proper places) have all been replaced. No fault codes in the computer. Fuel pump and regulator was checked. Help!