You need to determine if it is fuel or spark. I would have a squirt bottle of gas handy and when it starts to die, squirt a little gas in the throttle body to see if it will keep it running. If it does then you know it is running out of fuel if it doesn't then you know it is a spark issue.
When you say it starts right back up, no extended cranking or does it crank a little then start.
I don't think you can go wrong if it is cheap enough, he already replaced all the expensive stuff lol
Artificial Intelligence is no match for Natural Stupidity