2005 grand prix 3.8 misfire changed plugs ,wires,coil packs ,maf sensor was checked also ignition module was checked car still starts sucking down a lot of gas have not drove it only turn it on to see when changes were made if it fixed the problem any help would be great car has been driveing poorly would start the car and it would drive like crap but I would turn it off restart the problem would stop but if I couldn't stop to restart the car if I hit the gas pedal the check engine light would flash and when I would let off the gas it would stop so two days ago car was fine was at a light and all of a sudden car was shaken had no power and sounded weird ??????