I have a 97 Volvo 850. A couple weeks ago, it stalled a half dozen times while starting. The engine would turn over, start, run for a few seconds, then stall. Before calling for a tow truck, I started it up again, and it ran. After idling for a few minutes, it appeared to run smoothly. We drove home without a problem. When I took it into the shop, of course it wasn’t acting up. A little later, the technician called to say it acting up for him so he knew I wasn’t going crazy. He took it back to the shop, and it acted up again for another tech. They have since put their instruments on the car but it refuses to tell them anything. The check engine light works. All pressures are to spec. The fuel filter has been checked as well as all fuel lines. The car has not acted up now for over a week. The shop still can’t find the problem. I’m at my wit’s end and ready to take the car back again as I need it again.
Sounds like a fuel pump issue to me which can be very intermittent. I had my car parked in the ramp 50 miles from home and when I came out from my meeting it wouldn’t start. Called a tow truck to take it home to the shop and I rented a car. The tow driver said when he dropped it off at the shop, it started right up. Fuel pump. The jostling from the tow got it going again.
Count this as another vote for a weak fuel pump. I have never had a fuel pump die without causing trouble first.
A tech could hook up a fuel pressure gauge to the fuel rail and tape the gauge to the outside of the windshield (to avoid piping gasoline into the passenger compartment) and drive the car while watching the gauge to see if the fuel pressure is doing anything unusual during the various driving maneuvers.