Q: Van stalling - 1993 Chevrolet G30

My van ran out of gas one day and it stalled out on me. So, I filled the gas tank and continued driving. That same day, it stalled again and it took some time to restart after cranking a bit. After that, the van sat for hours before I started it up the next time. Then after driving a very short distance, it occurred again but this time I wasn't able to restart the car so I had to get it towed home. I was told that starter fluid might help so I spray some and it immediatelly started. The stalling kept occuring and the starter fluid helped each time. I had the fuel filter replaced in the meanwhile and used some Lucas fuel cleaner. I also tried premium gas. I had the fuel pump replaced with a new Bosch one. The stalling happened despite all that I've done. I went to a shop and had the intake cleaned. They tested the ignition control module as well. At the tuneup that was done just about 20 days ago, they had the spark plugs, the distributor, wires and rotor replaced with new parts. The stalling usually occurs at traffic lights. Do you have any idea why this is happening?