Need help on a 1984 chevy won't start

Hello this is first time so hope it goes right

need help have a 1984 chevy pickup truck 6.2 .

Here is what we did so far still wont start and run
it will start after cranking starter for abit and stalls

Change mechanical fuel pump
Changed the fuel shut off on top of ip pump.
changed fuel filter to a spine on type
changed all glow plugs and injectors
changed relay for glow plug on fire wall
new batteries
changed throttle sensor next to injection pump
changed glow plug card under dash
have tech manuals