Finally Cold Start Nightmare is Over (560SEL)
 

Finally I found the solution for the cold start problem (560SEL 1989).
Here is the whole story (read it if you want to have some experiance)
Previously I posted asking about the cold start problem. The problem started when I changed the EHA Bosch unit that is mounted on the fuel distributor. Then, on cold I won't start unless I disconnect the EHA wires. To solve this problem I changed and inspected the followings:

1. Front fuel accumulator
2. Back fuel accumulator
3. O2 sensor
4. Idle control computer
5. Idle valve
6. ABS/ASR control computer
7. Fuel pump relay
8. Vacuum leak
9. Fuel leak
10. Cold start valve (9th injector)
11. Water Temp. sensor
12. Fuel Fitting
13. Fuel injector seals

And other things that I can't remember...
Finally I changed the fuel distributor itself with a used one, and then, It worked somthly. I noticed that the Bosch part# for the old fuel distributor is different than the new one. After searching the Internet (http://www.mmedia.is/~joithor/atp/mercedes.htm) I discovered that the old one was for 500SL, 500SE or 500SEL NOT for the 560's. In ebay.com they are selling them as they are for the 560's, they'll mount but would never make the car smooth on idle like the engine is switched off. The old fuel distributor Bosch part# is 0 438 101 016 but the new installed one is 0 438 101 018. (Part# have been corrected)
Anyway I thank all of you for your support, and I'm still looking for a clean S600 1996~1998.
By the way, does anyone know the true Bosch part# for the fuel distributor for a 560SEL 1989?

All the best,

You are right but my car is 1989 and the old installed fuel distributor is for a 500SL, SE or SEL (1986~1991).

Try this
http://www.detali.ru/cat/oem_mb0.asp?TP=1

Thank you. Actually, I speak Russian as you speak Chinese.

YES they are, but only for the 560's.

I corrected the part numbers.