I second that. Crank Position Sensor as a guess if you don't have a code reader. I keep a Bosch CPS spare on hand. You'll need an E6 or E8 torx socket (can't remember) to remove the bolt that holds it. Videos of the replacement process are on YouTube. If ya have a 1/4" socket ratchet set with various extensions and ya have standard and metric sockets but none of the torx I'd recommend you buy this set of torx so you can deal with all the Mercedes/Euro torx bolts and screws. $25 and it should cover about any torx bolt or screw you come across. What you describe is very common with a CPS going bad... It is in a really hot part of the engine and as it heats up it then fails (while driving), then you pull over for a bit and wait and try to start with no success but as it cools down for a while you can then start again. With 90% certainty I'd bet its the CPS based on what you reported (but I could be wrong).