1989 200E. Engine will stall without warning
 

Imagine travelling at 110km/h or waiting for the traffic, the engine will just stop! The RPM meter will just drop to zero. I have to shift the gear to neutral and crank the engine hoping it starts. At times it does start. At times, I have to spend about 5mins cranking it. This problem has been going on for 6 months. There is no telling when it will happen. It can be 5 times a day or once in 2 weeks.
The fuel pump has been changed but to no avail. I have sent it to 3 different mechanics and none of them know the problem.
Any sound advice would be greatly appreciated. But don't tell me to:
1: Change car. I am short of $$$
2: Change engine. It is illegal here.

Thanx all
John
Singapore

A very common problem can be the fuel pump relay.........

The ignition crank sensor can also cause that type of problem.

You need to see if there is spark next time the engine WON'T start.