Volvo 940 stall

I bought a 1994 Volvo 940 Turbo about 3 weeks ago, with 156,000 miles on it. So far so good. But today after driving about 20 miles, it stalled while going over a railroad crossing. It rolled down the other side of the tracks, and I was able to coast to a side road. After it stopped, I tried cranking it again, but no start. Tried it 2 more times, nothing. I then pushed it off the road, and let it sit for about 5 minutes, cranked it, and it turned over. Drove for about another 3 miles, got it home, and now it starts no problem. The engine is running smoothly, and no loud crazy noises coming from it.

I've read in the other car threads stalling may be from a bad sensor, or not enough feul in the tank (or none!). I do have about 1/8 tank right now.

I am no mechanic, but what would cause a stalling problem in a Volvo 940?

Thanks