Anybody knows how to fix or have ran into a s4 b7 having a slight rough idle after coming to a stop ,no check engine lights ,no misfires ,vehicle runs fine but only slight rough like idle after coming to a stop ,could it be a faulty fuel pump ,or due to a aftermarket fuel filter ,filter been 2port in and 2port out type ,faulty throttle body assembly ,ecm issues [no tune] ,note also will run rough after stop then smooths out sometimes ,any response is welcome from anyone with a idea of what to check,replace or repaired.thanks