W126

My 82 300SD with 202,000 miles has been running hotter than it should be at highway speeds above 70 MPH. Not at red line but uncomfortably above the 100 degree mark and at 110 degrees ambient was getting close to red line last summer. At slower speeds and idling it does not run above 100.

My mechanic thinks he recalls there was a mfg modification to the water pump pulley in later year models like after 84/85 that replaced the pulley with a smaller one to make it turn faster.

Ok I am getting engine shake and it started about 4-5 months ago.
* When I start the car cold I do not get it.
* I can drive around in the city and it seems to never do it.
* If I drive on the highway and then exit after 5 or more minutes of sustained highway speeds (roughly)it does it and sometimes will not stop even after driving at city speeds. (UPDATE... it did it during city driving this morning once and then stopped at the next light, so I guess not it is just officially intermittent.
* I have replaced and adjusted the rack damper from upgrade bolt from MSource
* I have new fuel injectors from MSource (Monark ones)
* My car leaks nothing, not a drop from anywhere.

My automatic door looks just stopped working (all of them), everything else is fine. Where do I start? Where is the vacuum controller for the locks?
thanks
scott