Hi Steve,
Good to hear from you again. Did you get your tuning problem taken care of? Here's the link to my site which will show you the photo that I refered to in my previous post. And no, this is NOT the thermostat which controls the water temperature. This is the thermostat for the fuel injection pump. A very different creature.
http://www.geocities.com/thompintello/MercedesProject.html
The photo is on the second page of the site. Hope you're well. Cheers.
Thom