Thanks for the reply its petrol engine sorry forgot to mention that, ok heres the latest with this problem read just about everything realated to this problem but all suggestions have not worked for me list of what i have changed below Plugs HT leads Coil pack MAf sensor ICV sensor Injectors and rail Hose at back of inlet manifold and still got these problems Erratic idle, stalling when braking, lack of power got a mate to hook his scanner and its coming back with a missfire on 1 and 3 cylinders compression test we ran was ok, any ideas as to what could be causing this? cheers for any insights