2000 OX66 Will not start after 2-4 runs.

I have a 2000 VMAX 225 OX66 that starts great in the am. I run to 3-4 spots and go to start it, it fires, dies and then cranks with no fire. After anywhere from 30-60 minutes it will fire back up and the problem will go away for the rest of the day. Then the next day or a few later, the same thing.
Mechanics don't know what's wrong without it happening in the shop.

Today I unplugged the battery cables and let sit for 15 minutes and it started back up. Any thoughts?

[boats.net]

It would be hard to say but may be a low voltage problem possible a bad main relay.

ECM.

What does this do? Does it tell the engine to spark and tell the electronic fuel pump to kick on?
Mechanics are not able to get the motor to act up on the lake.