Makakio,

I had a similar problem with my jeep. i would start it and it would go up to high revs and wouldn't come down at all sometimes.

I had to have something called the idle speed sensor or something like that replaced. or The Idle Control valve not sure what it was,but since i had that part replaced the car never did it again.

If you can start your car when its in gear, then most likely the the Neutral Safety switch has a problem.

Some cars may not have this feature, but i would assume most cars do.

P.S. i'm not a tech, but just thought this would assist because of the similarity of the problem even though in my case it applied to a jeep and not a benz.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U