Idling speed uneven especially on summer days - occasionally the engine cuts off on 1997 Mercedes-Benz E420

When I come to a stop at a light or sign, the engine idling becomes uneven (200rpm to 700rpm). Car shakes. On a few occasions the engine has died. Also, on some days it takes a long time for the ignition to start the engine. Sometimes when coming to a stop, the ASR light comes on. When I start accelerating during a rolling stop, there is lack of power for a few seconds. Solved the problem of long starts by letting the air come on before turning the ignition. Don't know why it works.

Asked by for the 1997 Mercedes-Benz E420
Get the engine codes pulled and post on here so we can advise.