I've been having this issue for quite some time now and have had no success with several shops working on it. I drive an '85 240 with the Bosch fuel injected 2.3 NA redblock. The car will run for some time and then will shut off at seemingly random times. When it dies, it will sometimes start right back up but usually just crank with no start. Right before stalling, The RPMs will increase and decrease wildly, and the voltmeter will show no amps then amps when it's about to start again. I can't tell if this is an issue regarding electrical, fuel, or vacuum.
Here is a list of things that have been replaced in trying to fix the issue:
Engine wiring harness (new harness made by a shop for the car)
Fuel Pump Relay
All fuses were replaced with new ones and connections cleaned
ECU
Fuel filter
The MAF sensor was replaced about a year ago
Hall effect sensor

Any feedback would be greatly appreciated. I've also been checking all electrical connections that seem relevant to the issue and cleaning them with a deoxidizer.

 

Solder connections in the ignition control units can crack where the wiring harness is plugged in. The circuit board is covered in a clear silicone like substance - where you can see the cracks. I've not tried to remove that clear stuff to fix them - have only replaced them.

Before replacing anything else you need to figure out what stops working. Ign, fuel or injection. You can put a test light with two alligator clips on the flashing side of the coil - car stops, spin engine over but won't start, light flashes - you have ignition, must be something else. (sure it could be in the distributor cap/rotor button, but I'm hoping that has been checked. Same thing with the fuel pumps - car stops, spin engine, test light with alligator clip shows power to the fuel pump, and fuel pump buzzes - you should have fuel. If both those simple tests work - have to look further. How about the 25 amp fuse under the hood for the fuel injection system and it's connections to the battery?