1999 Chevrolet Suburban Fuel pressure

Why did the fuel pump get replaced to begin with?
If you spray starting fluid spray into the intake tube while someone is cranking the engine does the trunk start up and running if you meter the sprays into the intake tube?
This would give a clue if it fuel related.

Is there a security light on or flashing when cranking?
I've had vehicle security system causing this condition.

Did you happen to look closely to the fuel pump electrical connector? To see if there are any melted terminals. Usually the GM fuel pump I've done come with an updated electrical connector you cut and splice in a new connector to fit the new fuel pump?

Check the fuel lines to and from the fuel tank to make sure none of the fuel lines are pinched reducing fuel flow to and from the engine. If you have the means check the fuel pressure when cycling the ignition key. I believe most major auto parts store have a loaner tool program that allows you to rent tools or in this case a fuel pressure gauge. (Pressure should be above 55psi)

Its fuel delivery issue and I'd hate to tell you to drop the fuel tank again, but maybe you could lower it enough to disconnect the electrical terminal to the fuel pump. Check for any melted parts on the vehicle side connector and see if your getting power and ground to the fuel pump electrical connector (with the key on engine not running).

Splicing in new connections is real common on these fuel pumps.

You'll need to test for fuel pressure. If it is building pressure or is lacking enough pressure ( or fuel flow due to pinched lines) knowing what the fuel pump is doing. You'll need more answers as to why the engine stalls right after start up.
If you can keep the engine running with starting spray, you can assume everything else is functioning normally except the fuel system.

Adequate fuel and air, spark, timing and compression are all required for the engine to run.