My mini cooper s jcw 2004 sometimes has a problem sitting at its idle, it sometimes drops ever so slightly and the engine sounds like its miss fireing which it isnt but thats the kinda noise, instead of the constant hum of the engine its more of a racing hum then within 20 seconds it returns to the normal tick over. Its hard to explain ive tried recording it but it sorts itself out by the time im behind the car..but if i ever so slightly tap the throttle it raises then lowers just a tad too much as if its going to stall then sits perfect again. It still drives fine and stuff, im thinking maybe the air flow sensor or something..could be a plug i suppose or even the HT leads...

Thanks