hey guys my friend has an 05 G with vortech s/c on stock block and stock fuel system and his car has been acting up... when driving his car started jerking and the service engine light came on so he got it scanned at a shop but all it said was multiple random missfires. so the mechanic said its more than likely the spark plugs.... so we changed them and the car was still acting up. i think its either the coil packs or the injectors???? Any help??