You should read up on EHA current. It represents ALL of the electronic correction to an otherwise hydro/mechanical fuel metering system.
The fail safe/limp home characteristics of this system are the best. When Mooney (sp?) wanted to use a Porsche Carrera motor in one of their planes they went backwards in fuel design and installed a K-jet fuel system instead of the Motronic that the Carrera came with.
The EHA when disconnected leaves the car with a system that runs perfectly warm. Things that will stop you are fuel pump/fuel pump relay, crank sensor, coil, and possibly some defect in the EHA control (it will work fine without it but there are ways it can shut you down - disconnect it when hot and evaluate).
There are another group of things that cause the car to die at idle, but to shut down while driving usually is one of the above.
Bosch Master, ASE Master, L1
33 years MB technician