Hello!
My 95 S320 (made in late 94) is currently sitting in my auto shop because myself and my mechanic are befuddled with this and here is why:

The car started moving with a stop-and-go motion just jerking suddenly, not moving out of 2nd gear.
The car has never done this before, no transmission issues either.
My mechanic determined that the fuel rails we not holding fuel pressure. the fuel pressure regulator has been changed and works fine.
At first, we though maybe it was a fuel pump so the car was basically choking like a fish with little to no water and then we figured out that the throttle body was also acting up.
The throttle body has no electrical input from its plug. We checked to see if the throttle body still worked by applying power to it and it works as it should aside from not having power when it is plugged it.
The relay for the throttle body also works and has power. The wiring harness going between the two is one that typically does not go bad.
After checking these things, we found that the over-voltage protection unit in this model is part of a computer which was not working. It was not letting the throttle body and fuel pump work. We replaced that unit and it worked for a couple minutes before the car started jerking through the parking lot.

So now, my question is, why has this part gone bad a second time?
My theory lies in something to do with electrical connections that are sending the improper voltage. Low or high? I don't know. I don't completely understand what Diodes are, and same with resistors or what they look like. I don't even know if I'm looking in the right place but I'd like some feedback to let me know if I might be on the right track.
Also, could anyone tell me what direction these electrical connections come from? Where does my over-voltage protection unit that controls the fuel get its power? Is the power directly from the alternator and if I need to look at a resistor? Where would I find it and what does it look like?