You need to try checking to see if it's getting spark when that happens. The easiest way of doing so is by taking one of the plug wires off the spark plug, putting a spare spark plug in it, and lay it on an engine ground. Then while you're watching the spark plug (keep your hands free of the belts!) have somebody turn it over. If you see spark then you know your problem is on the fuel side of things. If not then it's narrowed down to spark which could be an ignition module, or the pickup in the distributor. Both of which can cause the symptoms you're speaking of. Of course it could also be other things, but those are very likely culprits.