2nd Jul 2022, 12:38
Does it fail to re-start after the engine has warmed up, does it always pretty much start from cold? Try checking the relay that controls the fuel pump, it probably is a general engine relay that controls that plus some other functions like the ECU. It's possible that there may be a hairline crack in the solder within the relay's circuit board which expands and cuts off when warmed up.
1st Jul 2022, 20:16
It seems the Merc engine has reached the end of its life. Probably no solution other than a complete engine rebuild.