Recently I've been having the Hot restart troubles followed by the "here it comes again.." miss & rough Idle on my 1987 300SE Euro. I again did a lot of reading , a few tests of my own and consulted my Mechanic. Here is what happened and what I did.
Following a fuel pressure test and getting stuck in a major intersection in town, I replaced the fuel pump (4 yrs old only!) and filter (was 1yr old- but since I was already there...) I actually thought this was very early for a fuel pump to fail, but learned of other cases where that had occurred. This action seemed to cure the hot restart - Not completely though. The accumulator was replaced too, a year ago, so for good measure and thinking of possible leaking injectors, I replaced the injector seals (7 yrs. old) and the Spark Plugs that had only 20K on them but looked bad. On the other hand, The rotor&cap as well as the plug wires only had about 30k(4yrs) on them so I was sure I was OK there-

In the few weeks this was all taking place the rough Idle/Miss issue was developing rapidly. I checked the Idle valve & hoses. They were good. I removed the fuel pump relay and bridged it just to make sure the relay had not gone south.- The miss was still there, so I deducted the relay was good. The OVP fuses were good, nor did the OVP exhibit any of the other signs of going bad (the check engine light, the ABS light etc )
I then noticed the #1 plug was fouling quickly so I replaced that injector with an old one I had to see if indeed the Injector - rather than it's seal was leaking. This was getting very frustrating - Yet all the stuff I had mentioned above as changing was good maintenance, even if a little premature.
The #1 plug was still fouled , so I thought of one last move before facing unknowns like a coil, which I did not think it was, or the big ticket items which I cannot diagnose myself like the distributer or the Idle control computer.
My last move was to go ahead and check the Cap & Rotor anyhow. That lower hard to get to bolt, plus the knowledge that "on paper" they should be good, made me shy away from digging in there. Well to my great surprise and relief- there it was...Victory at last. All torn apart inside !!!!
I am not sure why, but the Distributer Cap is worn out unevenly . The #1 slot is completely gone !! I thought it would wear out evenly. So something is out of balance. What does this indicate about the engine if anything ?