Hi again... :^)
I haven't heard that the vacuum valve is a regular replacement item. My car was shifting very roughly and it turned out to be vacuum leaks and misrouting of vacuum lines. Has your car always been this way?
The EGR valve is not a regular replacement item but should be checked periodically. There is a hole on the top of it through which you can see the plunger go up and down if you pull on the cruise control arm. I use a flashlight to see better. Besides, that thing is really expensive...
Hoping this helps.
1982 300D - <A HREF="http://members.xoom.com/nicodore/