my car did exactly the same, but used to cut out too. i got it plugged in, loads of faults, knock sensor below 8, misfiring on cylinders 2 and 4, sky high emissions, and the power of a fart in first and second gear below 2.5-3k rpms. got new plugs and leads, no different. new fuel pump, still the same. got the injectors checked out too. then the guy when checking the lamda sensor said it was shot. so replaced that. he plugged it in again a month later (after resetting the ecu) and there were no more faults and the car was sweet as a nut