Can anyone help...i recently had a battery die on my 328i E46. I replaced it and since then i have had idle troubles. The revs jump about 500rpm at idle up and down almost stalling. The exhaust note is also spluttering. It seems ok at speed. The battery change maybe a coincidence. But i had no problems before. Why has a problem suddenly occurred. The car has had a FULL service at bmw so not plugs/filter etc. Could dirt have got into filter as has had fuel light on. I would take for diagnostic but have spent A fortune on it recently! Can anyone give me a answer based on these problems. Thanks! Stuart.