Your reply is extremely informative. Thank you. After I left the smog place I took it to a Mercedes only shop and they too didn't know why the DTC's were still in memory after re-starting the car. He diagnosed the car as most likely the wiring harness. (he might be right... just for the wrong reasons)
Just goes to show... it is really tough to find a '92-95 W140 expert; I can't tell you how many times I receive information or repairs based on total guesses.
The smog place didn't charge me and I will gladly go back and educate them. They're a good place and I take my less technical vehicles to them. I have an appointment with a smog referee tomorrow AM.
Joel P. Davis