my calais starts and idles fine also cruises along without a hitch but as soon as she's under load it coughs and splutters like a pig and if its idling and i give it a sharp rev it misses and backfires i done a diagnostic check and came up with code 47 - crank angle referance signal missing i changed coil pack/DFI module thinking it might have been that but still running like a pig what else could it be? doubt its the actual CAS because it starts and runs fine and doesnt stall at all any one else had this problem? **HELP**