Newbie here. I just now have experienced the same problem with my e420, only it is raining and last week we accidentally ran over a large dog carcas and the lower splash plate had to be removed. It needs to be replaced. It was running fine but yesterday when my wife started it to drive home from work, she said it took a couple of tries which was odd. I was about to take off on a trip about 45 min away and when I started it, it was running rough. I thought I had a vacuum hose disconnected so I checked under the hood. When I removed the air cover and found no loose hoses it ran even more roughly. Then I replaced it, turned it off, then back on and it only barely started, the accelerator pedal wasn't causing the idle to move up from barely on. The splash plate did have a little air intake channel on it, could water vapor in the air have caused it? This is the next day and it still doesn't run unless I step on it. It is still rainy.