Help!!

[Chevy GMT400]

Hi thanks for the add I'm needing some help if possible I have a 1990 Chevy GMT400 has a TBI 5.7 in it and I can take it out make a good solid hit on the street with it and it has full power with absolutely no hesitation.

Then I'll try to make another one and it spits and sputters like it's getting no fuel now if I drive it normal it does fine second I try to give it WOT it just cuts out again

until I stop and turn the key off start it back up and then I can stand on it again with absolutely no hesitation then it starts all over again

any help would be great thanks.

Also I have replaced everything that has to do with fuel New steel braided fuel lines from summit new summit fuel filter and A new Summit fuel pump with all new fittings and new fuel cell.

And still haven the same problem

ANY thoughts