Just replaced fuel pump in 2000 chevy 2500 and when put in gear feels like it might die but fine once it gets going?

have you checked to see if engine is firing? ignition module can go bad and you would loose fire and fuel at the same time. i replaced one on a chevy truck last week and it was located beside the ignition coil.

CHECK FUEL FILTER ,,,,,,

Have you scanned for fault codes? How about the Throttle position sensor, have you tested it?

can be a number of problems start by checking the vacuum lines for crack or leaks then fuel pressure -if low or cutting out change fuel filter and check fuel pump==-check -clean or repair /replace egr valve clean first with a carb cleaner valve usually builds up with carbon -check and clean or repair throttle body possible clogging-or adjustments

your lift pump is shot. its on the back side of the motor behind the fuel filter housing

The fuel pump should be in the 20s. Also it could be losing presure slowly. Leave the fuel pump pressure gage on for at least 2 to 3 hours to see if it is losing pressure - It's a start

Let me tell you the truth, its your fuel pump. everybody tells you to check youre injectors and replace youre fuel filter but the truth is its your pump. all chevy and gmc models have that problem. I just replaced mine. i have a 2001 chevy 2500hd also with the 6.0 and did the exact same thing. I bought a fuel pump and put it in and BINGO truck runs and starts like new. TRUST ME MAN

MOST LIKELY A WEAK FUEL PUMP

check for power too the pump first with a test light if you have power too it then the pump is bad if not youve got a short some gms also have a fuse check for that also

Sounds like a fuel mixture/vacuum problem. Vacuum advance line on the distributor could be loose/leaking/collapsed.