Is the fuel pump getting electricity when this happens?

I would connect wires and a voltmeter to the wires AT the fuel pump so I could see if it is getting power or not.

If it is getting electricity when this happens, then I would connect a fuel pressure gauge to be sure it is in fact losing fuel pressure when this happens.

The trick to troubleshooting intermittent problems is to be able to "see" what is going on by connecting monitoring test equipment.