Jmaannnnn

Replace the rubber gas lines going to fuel assembly from metal gas line from vehicle frame had same problem at one time and that was the problem rubber line was collapsing shutting off gas flow then returning to normal size once it set for awhile. Not saying this is your problem but something you may want to look into.

release fuel pressure with a hose on the schrader valve see if that helps , don't start any fires , if it starts then replace the fuel pressure regulator ,

Thanks will try out both and let u guys know