Car has done this for awhile, mechanics couldnt find fault, its a little disconcerting sometimes as it can do it when acclerating from lights/crossing a road/going around a round about. Under no/low load, WOT only, from idle only, the engine hesitates and splutters around before accelerating. Sometimes it lasts seconds, sometimes its just a cough. Only does it from idle, and otherwise works perfectly.  No fault codes. Nadda. Ive reset the DME by pulling the battery. No change,