300SE -90 stalls but then starts again...?

This morning, driving to work with kids aboard at 80 km/h, suddenly the car does not respond to gas pedal at all. I pull on the side of the road, engine dies, I switch off the ignition and go check under the hood. Nothing unusual, slam the hood shut and turn the ignition: starts immediately and I drive off with no further problems !

I have had the similar issue a couple of times during the last months, always been able to drive off after a while of pondering. I do not know whether this is related but sometimes after filling her up, the car just cranks but does not start... after waiting a couple of minutes it starts again. I changed a new battery some weeks ago, nothing else has been done in order to cure this phenomenon. Any ideas what to check next (new fuel filter installed last fall as well as the usual cap, rotor, wires...)

Exciting to leave work in an hour and see if I get home