Hello, I have a low miler 300SE, and its got a misfire when warm.

When the engine is cold, the car starts and idles like normal, drives good and seems to have no issue, when it's warm, it runs slightly uneven and sometimes it misses, if you are driving at high speed and let go of the throttle to slow down, it will start to miss when accelerating again.
When at idle, it will run eneven, and miss after 5-10 seconds, it just misses a few strokes, but it varies. If you hold the brake and put it in D, it will run at about 550 rpm and miss even more. The exhaust smoke is too much grey too.
On rare occasions, it have not started when warm, I had to wait till the engine cooled down a bit. I have changed the coolant sensors, but I'm not sure if that solved the problem, it's cold weather outside these days.

I have changed all parts for the ignition, everything is correct to the m103. New EHA adjusted by MB too.
I think it can be one of these parts that can make it run like it does

-Injector is leaking (IR thermometer at cylinder 1 and 4 show lower temperature then the others)
-Fuel accumelator that can not adjust the pressure when lowering speed
-Plugged fuel filter (time for change)
-OVP relay starting for fail (mine is from 89)
-Voltage regulator (I heard they can cause issues like this)
-Running too rich (It did get Co adjustment when MB replaced the EHA, but the engine was missing still)
-Engine timing, the light showed at idle 1tdc, when at 3000rpm, I think it showed 30, can't remember.
I just recently changed the valve seals that were bad, I noticed the engine used oil, and the spark plugs were black. Although replacing them did not fix my problem, it did help allot. It solved my hesitation issue, and gave some freshness to the engine.

Any of you guys had this problem before? Any help would be much appreciated