I have 1998 E300D Turbo Diesel. Occasionally when I turn the key, it turns but nothing happens. Try it a couple more times and it usually starts. Lately, the engine has quit a couple of times while driving -- usually when slowing down to make a turn. I turn off and on again and it usually starts. A month ago I replaced a Crank Position sensor - (intermittent engine quitting, confirmed by OBD hookup). Could this be the same problem? OBD shows nothing.

 

I would start with the k40 relay on the passenger side engine compartment control unit box. It runs about 100-150 bucks and will display these symptoms. Relays will fail when with inertia from turning and accelerating/braking. Other than that, if you have some fuel lines leaking, they can actually pull air into the lines and cause stalling/no start conditions. This is not to be overlooked but I would shoot for the k40 first.