Is this a crank sensor problem?
 

My 1999 E320 has 150k miles and has had few issues. Did replace the catalytic converter a month ago. Recently drove to dinner, came out an hour later and it wouldn't start. Tried several times but it wouldn't turn over. After 15 minutes it started right up. Drove it half a mile and it died at a stop light but started right up. Drove it a couple of miles on the freeway and it died. Waited 30 minutes for a tow and the driver drove it on to the flatbed. It's been starting up w/o a problem for several days. My local mechanic says the diagnostics didn't show anything. Other threads have said that a crank sensor problem won't show up on the diagnostics. Appears hooking it up again at my Mercedes dealer for $179! would be a waste of $$. Still drives like a dream but I'm afraid to drive it anywhere. Thanks for any input.

the fact that it sat for an hour during dinner makes me think that its not the crank sensor because they normally fail only when hot and will start up when leaving them sit to cool down. try using another key if you have one. bad keys do weird stuff sometime. so eliminate that by trying another key/remote first. crank sensors are pretty cheap and I recommend going with a bosch sensor. could be a fuel issue also.

Sounds like a crank sensor to me. When the car sits for an hour that is not long enough to cool down. I would start their if it was up to me.

Deff the problem my 05 was doing the same thing. Turned out it was this sensor. I replaced mine before I was going to take it in. The part was 60 deer so I changed it and no problem since. hope it helps!

Fuel filter as well, if you haven't changed it.