I also am have some idle speed problems with my 82 500 sl and have read your comments on the aux air valve. I will have to check mine, thanks for the info.
I was woundering if you would happen to know wat the vacum line in your picture of the warm up compensator does? The on with the arrow next to it.
I had my warm up compensator replaced with a second had unit, which does not have this line and the mechanic has just blocked the vacum line up. Could this be some of my problem?

When my car gets to operating temp (more when it's quit warm) the idle drops very low. I have adjusted the idle screw to bring the idle up to compensate, but when it is cold the idle is alot higher than it should be. The idle is also high when it's warm and you put in in park and take the load of the engine.

If you could shed any light in this vacum line that would be great.

Regards

Damian