i have a 1.8 zetec focus, when im driving the car it randomly stutters just after changing gear but as i accelerate it clears itself, when stopped it drops below 1000 revs an the engine judders a feels like its going to stall an occasionally does stall, also the spedo stops working for a few mins then starts again. i dont know if this is related, i have been told it might be the maff sensor is there a way of testing this,if any other suggestions i would be grateful