Thanks Peter (psfred) for your help with trying to cure the rough Idle on my 1987 300SE/Euro. I finally got to replace the two breather hoses on the Idle Valve. Gladly I must say that Idling has never been better. There is only a hint of an occational shudder when the car comes to a stop. It is Almost MB perfect.
This was the last chapter, I hope , after replacing fuel pump& filter, plugs ,wires , cap , rotor and clean flushing the Idle valve itself.
Like you said the hoses were a bear to replace , especially the one to the Manifold. I did manage to do it myself though, both from the top and bottom . Had to remove the cold start valve though, in order to fit the hose into position.

I was wondering if members here would believe that the the changing seasons could have something to do with better Idling as well. It is colder and perhaps the Hoses and fittings and valves do not expand as much..any thoughts on that ?