After reading many of the threads on various topics ... this is the fix that has worked so far.

I lubricated the top of the distributor's shaft with ATF fluid a couple of times over a 3 week period. It seemed to break-loose a sticking advance mechanism.

Now the car doesn't stall or run bad after freeway driving like it has since I got it.

Thanks to this forum, I'm enjoying the world of "Vintage Mercedes".

Thanks to all!

Richard