I have a 1999 buick regal ls dying.

I have a 1999 buick regal ls and you drive down the road and it dies. Then you can crank back up sometimes and sometimes it takes about 10 min. My 1999 regal had the samilar problem. on the day before yesterday, my wife drove about 30 min (high way) to work, (at 6:40 pm)when she arrived her company braking for parking, engine died and no way to get it started (several guys tried it). At 2:00 am next day, when I picked her up for home, I tried to start the car and it could run. Then my wife drove the regal home and park in garage well no problem (I drove my car followed her). I wondered what's the problem, we wanted to make a general check soon. However, yesterday evening, my wife drove it to work as usually, about 20 min when she stopped for a red light, she could not start the car to run (at 6:30 pm), Same problem occurred like the day before. The car was pushed to side way (on a high way). I was called to have a look and send her to work. After there hours later, I drove my friend to have a check, the car could be started and run again. So we drove the two cars home. After 10 min, it died again, so we left it on sideway. At about 2:30am next day (today), I tried to drove it again, it didn't start. At 10am today morning, could started it and drove about 1 km, I stopped it (turned off engine). Then I tried to started it again, it died again. Then it was towed to my drive way at about 10:30am. At 3pm afternoon, I could start it and adjust parking position on my driveway. I would like to know what's the problem and how to fix it. Someones think it's fuel filter or related problem, someone says maw be electrical issue or else. Any opinions and solution?