got at 05 grand prix with 3.8 series 3, im having an issue that doesnt turn on service engine light so shops cant find out whats wrong. my car drives fine at slower speeds but when on highway and im speeding up and my foot is on the pedal the car will act as if i took footoff pedal and then will go back to normal and it will do this several times and then stall out after about 5mins of trying to start back up it will start and run fine all the while never turning check engine light on, ive changed crankshaft position sensor and ignition module with no luck please help me thanks
