You can also probably rent a fuel pressure tester from an auto parts store if you don’t have one. Connecting it is a little bit of a hassle (you need to remove the banjo bolt from the back of the fuel rail and use an adapter - there is no pre-existing test port) but it will instantly confirm if...
Does your dash totally go out when this happens? When I had a short impacting my ECM, I'd hit a bump, and everything would die. Engine stalled, dash went totally dark, no lights. It was instant stall and death. The way you describe it, it almost sounds like you are losing fuel pressure.