I have a 97 Lumina 3.1 liter. Mileage at testing. Fuel pressure at rail. Key on engine off: 35psi, Engine Running. 34psi: Engine running vacuum line removed from regulator: 42psi.
Removed return line end next to fuel filter, connected clear plastic tubing and ran to fuel filler tank. Pinched off hose, pressure went above 60psi. That is completely pinched off to get that pressure. The pump was drawing 12.5amps , read at fuel pump relay.
This car now has 152,000miles on her and is running perfect. If you are close to these numbers I would say the pump is good.