Fuel pump question

[79gmcsierragrande]

I was under the hood with it running and there was gas coming out of the fuel pump. So I went to Napa got a new fuel pump. I replaced both gaskets and made sure the rod was put back in the right way. The truck sputters like it’s running out of gas when it’s idling but not all the time. It runs good and doesn’t hesitate when I step on the gas while I’m moving. This morning I got stuck in an intersection when the truck died out and wouldn’t start as if I ran out of gas. It was running fine before the pump change so I’m thinking it’s a bad pump but is there anything I should check or adjust before I take the pump back to Napa?