1992 Chevy Astro Insuficient Fuel/will not stay running

Engine Performance problem
1992 Chevy Astro 6 cyl Two Wheel Drive Automatic

I have measured the output of fuel pump and it was more than my Haynes repair manuel said was needed.

I drained all fuel and refueled with fresh premium grade gas.

I installed a new fuel filter, regulator diaphram, fuel meter gaskets, and fuel injector o rings.

Cranking engine with injectors disconnected allowed no fuel from injectors, then connected injectors and observe fuel from both injectors.
Engine will start but will not stay running. If throttle is opened the rpms will increase momentairly and then cause the engine to die which is the orignal symptom I have had from the beginning. This occured abruptly. I had driven the van to a shop to have a current safety inspection done and engine was running normally but when the person strated the engine to do the test this symptom appeared. He said it may be bad gas which is why I drained the gas and refueled with no change.

What other component can restrict the amount of fuel from the injectors? Or what else could cause my problem? If it is not fuel related?