I have a 1990 190E 2.6 auto. Sometimes it runs ok and sometimes it will not hold a tickover and just keeps stopping. I suspect a fuelling fault as the plugs are all really black and sooty and when it is revved at standstill there is a large soot stain on the floor at the exhaust exit.
Has anyone any ideas, thanks, Mark...

 

your fuel distributor is the problem.

check for any air leaks first. this causes lean mixture and soot.

what is tickover? when does it run fine and run faulty? temperature related? speed?

 

The engine stopping is usually when cold, and the tickover is about 900 cold choke and 750 warm tickover. Although the engine runs well and no hesitation at any speed, the tickover is not totally smooth as i would expect from a straight six. Mark....