Rev 318 in park, slows down and stalls..case study.

You need to do a fuel deliver test.
To eliminate a supply side issue

The pump is working cuz it starts up again . But there is probably a supply side restriction or the pump is sucking air, or as mentioned; the tank is not venting, altho that is not on my radar, cuz it starts right up again with minimal cranking. My guess is the fuel level got too low for the low-speed jets. I don't think the bowl was empty cuz the crank-time was relatively short.
I had a similar problem when the rubber jumper from the sender nipple to the main line started sucking air; but the crank time was longer, and sometimes I had to wait a really long time.
But in your case I just think the pump is weak or there is a supply-side restriction and the the fuel delivery test will sort it out right quick.