Priming system not working

I got a 1990 chevy silverado with a 350 in it
4x4 it sat up for five years we tried to crank
it and it wouldn't start we narrowed down
what was wrong with it and replaced th
distributer and spark plugs and the plug
wires and it ran fine we shut it down came
back the next day it won't start we. Replace
the fuel pump and fuel pump relay th pump
works but it won't start so we replace the
ignition control module oil pressure sensor
still won't start. When we pour gas in the
throttle body it will start for a second and
die .I can't figure out why it won't prime gas .
if I was unclear on some part tell me and I'll
explain better .