1995 W140 S500 Misfire/ rough idling, Need assistance to restore/ refresh.

[140_S500LD]

Have a UK 1995 W140 S500 PF
has 125,000 miles, car cuts has a rough idle and misfiring, it wasnt doing this when i first got it,(1 day) was idling a bit rough lowering and going back to stable.
anything to look out for?

It has new fuel pump. is this a fuel issue or electronics issue, sometimes truggles to start, example i drove around the my area today drove fine full power,
with the misfire and all, parked it and tried starting it up again and now its not starting, it cranks over but no spark anymore.

i know the condition of the car and my intentions are to restore it, so where shall i start and how would i diagnose certain things.
looming looks nice no cracks from what i can see.
thanks in advance

 

[AMGeed]

Sounds like the car would benefit from diagnostics at a Mercedes specialist.
Your issue could be plugs/crank sensor/any one of the 8 coil packs being faulty, to a fuelling problem.
Star diagnostics. the Mercedes system can often pinpoint the issue and Mercedes specialists should have this as a matter of course.

What is your location?
Maybe someone here can recommend a good specialist nearby. Be prepared to travel a bit though. A good indy is worth the trip.

 

[alexanderfoti]

Being a m119 it will have two ignition caps and rotors, these are the most likely culprit for your description of the fault imo.