Pull the coil wire off of the coil. Hold it up just high enough from the coil tower to see the wire spark to the coil when idling. (Might want to use some insulated pliers for this lol)
When the engine stops, does the spark stop at exactly the same time, or do you get spark for the few revolutions of the engine as it dies?
If you lose spark immediately, I would suspect a TFI module dropping out. It you get a few sparks to the coil as the engine dies, then you can assume, for the most part, that it is not ignition related.