2000 Volvo s80 shuts down while driving

Hello, It sounds like unintentional grounding to the chassis during the fuel pump repair. If the battery was disconnected and reconnected improperly, or if it was left connected during the replacement of the fuel pump, there easily could be damage to various electronic components on the vehicle. That would include wiring harnesses and fuses as well. When the vehicle dies when getting hot, a great place to start looking is the main relay. If heat expansion causes the relay to open, the engine will shut off right away, and cooling down will be needed before it will restart. Immobilizer and alarm systems will prevent the car from starting, but will not cause the car to stop running when already running in gear. However, you should have these checked out so you don't end up stuck with a car that won't start at the grocery store or work, etc..