stopped while driving on 1994 Volvo 850

Since last summer,I had replaced the fuel ejector, fuel pump, spark plug, speed switch sensor , the car still stopped when I was driving on the road. I could restart it but it might stop again , it happened twice, the Volvo shop cannot find the problem. What else can the problem be?

Asked by for the 1994 Volvo 850
Usually once the fuel pumps on these cars quit, they are done. Under the hood next to the windsheild there is a fuse box. When you pull the lid off there is another part that has four screws in it. If you take out those four screws and take the top off the part that doesn't have fuses you will see some relays. The fuel relay will be green or red about an inch wide and two inches long. Look at the lid it will tell you which is the fuel relay. Pull it out and replace it. That should fix you up.
2 answers
The fuel pump is the main culprit when this problem occurs. I would also replace the fuel pump relay.
Is your check engine light on?
Have you had any fault codes stored?