Ihave a m35 rs4 with vq25det.
Recently when idling at lights and etc , the car will go from a normal idle speed and with out any warning drop in revs. It will then stall or almost stall. If it doesnt stall it will just barely idle for ten seconds or so then return to normal. A jab of the excelerator brings it back too. It doesnt make a difference day or night and whether in gear or not. While it is idling slow ( rough) , i have notice black sooty smoke from the exhaust. I might be wrong but it also feels like there is a lack of boost when encouraged to do so,
Can people please tell me what i should be looking for to get this issue sorted, or give advice of any sort.
cheers!