I remember when working in the tropics back in the seventies.
The job required series II Land Rover 6 cylinder versions. These cars had a lousy location for the coil - too close to the exhaust manifolds and under a leak spot off the hood. You needed to carry a spare coil around for rainy days or for going on long trips. Mountainous areas required to carry 2 spare coils and when they all 3 heated up they required an ice water soaked rag around them to keep them going.
When they were too hot - no go.

The moral of this story is that electronic components function differently under operating conditions than they do on the bench. That is why I inquired whether or not the components were actually changed out and run on the car rather than just a static test.

What is that part, I don't recognize it? Is it on the M103 as well?

Throttle micro-switch. The one in the foto is off a M103. Resides under EHA - next to Fuel distributor.

Throwing a wild dart at you. Is the transmission downshifting correctly. Downshift manually to first gear. If you are not stalling then we need to look further. Its a 1988 mercedes. Count the gears as you shift all the way to cruising speed. If you have four gears then I am going to wonder if your torque converter is coupled correctly when you are in the lower gears. Hydraulic coupling is necessary. Mechanical coupling is used to cool the tranny in higher gear. If the mechanical coupling is not released into hydraulic coupling then therin lies your problem.
Coupling from the engine to the transmission at idle is only possible in hydraulic coupling. (torque converter)

As has already been mentioned, this is impossible, because this car does not have a locking torque converter.

I just swapped it this morning, no difference, the car stalled after a half hour while going to the store.
I did however learn something about how it picks up the spinning of a disk and turns it into a signal. Pretty nifty!

I did another fuel pressure test now that I have a new fuel accumulator in the line. The fuel pressure on the main line did not go over 4 Bar. I think I am going to close this chapter and competition and call it fuel pump problem. It's new so I called the vendor and this time they took my car's serial number. Guess what, I had the wrong pump all along! A whole year of misery and all it was is the wrong part.
Thanks guys for your input.

You may want to look at one more thing. I had a simular problem that I chased for a couple of months. There is another symptom going on at the same time which made it harder to sort out, but when I finally got to the bottom of it, all it required to fix it was adding a lock washer and tightening a nut. The car would be driving fine then would stall and be completely dead. After a minute or two it would come back to life start right up and run fine. A number of members pointed me toward loose battery cables, and when I checked them they were clean and tight. I never noticed that the B+ wire was attached to the positive cable with a nut until much later. When I did, I found out that it was very loose, not even finger tight. I took it off, cleaned the wire and the stud, and the spot on the inner fender where it connected to the rest of the wiring harness, then reassembled everything with new nuts and washers and lock washers and the problem has never returned. I still have the other stalling issue on initial startup but I think I'm closing in on it.

No chance it will be my battery terminals. The battery is new and I have disconnected and connected it over and over with no issues.
Right now I am going to wait on the fuel pump, install it, test the car then start another chapter in this stalling saga.

That's what I said. Every other car I can ever remember either had the B+ coming off the starter or molded into the main battery terminal. I never saw one that was nutted to a stud on the terminal before. Boy was I surprised when I finally saw it.

I have never heard/seen this. What does it do exactly?

Have you conducted a proper vacuum test on the vehicle?
A full emissions test? And not from the tail pipe either. From the engine compartment.

Codes are sometimes not thrown. I am not a mercedes mechanic.

Get a pin to pin check on all wires to and from that computer. They can be a culprit.
Good grounding is a must. Everywhere.
Disconnect each connection and inspect for corrosion. Clean and use the clear dielectric stuff from the tube when reconnecting. Every connection you can find.

I am finding connections with corrosion all the time.

It shuts off fuel while coasting with no throttle applied, and tells the system to idle once the engine speed comes down to idle range.

I am of the opinion that taking a Bosch injected vehicle to a dealer or indie is a mugs game. Most of the dealers and indies in my city send the cars with injection problems to a Bosch franchised injection specialist. These guys only do one thing - Bosch injections. They have all the technological equipment and know how - inherently more knowledge than the average mechanic.

A full service, system adjustment, system clean-out, and diagnosis costs around $ 150.00 at the Bosch specialist. He will then inform you of suss items. AND they know exzactly what they are doing.

Haphazardly trying to guess what is going wrong with a KE injection system with a multitude of expensive individual parts can lead to an expense much more than the sum of the problem as indicated at the start of this thread.

At least the professor has replaced do much on the injection system that he should have no real problem for years - caveat - after it is tuned properly with the correct equipment.

Hmm I never thought of that myself. I may actually do what you said and take my wagon in that has idle issues. Thanks Ivan!