I had a similar problem a couple yars ago. It ended up being the thrust bearing, it failed and on hard stops the crank shaft was actually sliding forward in the mains. When the middle counterweight contacted the main web of the engine block the engine would stall. It always restarted except for the last time....

When I tore it apart I found out that the crank shaft had eaten away about 1/4" of the material in the main web. I had to toss the engine it was so far gone.

For your sake I hope it is a fuel issue.

Barry