1992 Pontiac Grand Prix Stalled And Won't Start

I was driving my 1992 Pontiac Grand Prix Se and right after I accelerated from a stop sign, my engine stalled. We had to push the car to the side of the road and park it. This was the second or third time this had happened, and the other times I would put it into park and start it right back up with no problems. It didn't start back up this time. I have a friend who does mechanic work he did some tests. It is not a timing chain or the spark plugs. He thinks that it is something with the fuel. He looked at the fuel filter and cleaned out some dirt from it and then it started back up just fine. He lowered it down from the jack and then it wouldn't start again. The fact that it started up after he messed with the fuel filter points to that being the problem but he thinks it's something more. The engine cranks but won't turn over to start. Is it just the fuel filter or could it be the fuel pump?