time related problem

[Philip Greer]

Hi new member from United kingdom. I work week on week off on English Channel Ferries. Start after a week away and my 1992 S500 Sel runs fine if
you do not push accelerator into kick down. Do this and engine feels like its lost a couple of cylinders.After 15 miles clears and all is fine for rest of week off.Same thing happens after only 2 or 3 days parked up at home on leave.
Plug in Snap-On Tools diagonistic unit and shows Safety Fuel Shut Off Signal
LHS No 1/3. Ex MB technician says poss. its the electronic accelerator unit.
1300 US dollars in UK !!!Ouch! and you just cannot buy a second hand one from one of our many MB wreckers yards and plug it in. It needs to be matched to car.???He says. Anyone heard of this type of fault. Do all my own spannering and am electronics engineer.