I was coming back from a family outing in my focus tddi . I was doing around 70/80 mph and the car seemed to miss ,as a petrol car would it then cleared . it only happend for a second . It happened again under acceleration out of a round about and again when i floored the throttle from doing around 10 mph ,the engine seemed to bog down and then picked up . does any one recognise these symptoms . i thought may be the air flow mass meter .