Ok so I just bought a 1998 Tahoe 5.7 and ran strong started strong after I put in new battery in. Well truck like to bog out if I really give it a heavy foot it has gotten better i don't know what it is. But now it cranks and won't start unless I put gas down in the throttle body.
Here is a list of what I have done
1. Replaced fuel pressure regulator
2. Replaced distributor cap and all parts along with it
3. Temp cooling sensor
4. Cut off the cats
5. Replaced fuel filter
6. Checked mass air flow sensor
7. Checked fuel pump and is pumping fuel
8. checked fuel pressure it's at 50 psi when I turn key and pump comes on then when I go to start it its at 40 psi.
Not sure if the fuel injection is clogged up and not getting fuel in motor because fuel filter was pretty bad and clogged up.

But once truck is on after I put fuel in the throttle body it dose not shut off. I'm so lost on what to do and I don't want to keep throwing parts at this thing so please if anyone has any answers please help a guy out so lost on what to do next.

 

Welcome to the forum. It sounds like there is something between the fuel rail and the throttle body if you have to put gas in it to start it. Need to remove throttle body and ensure that there are no restrictions in the fuel passages.

 

Should I try pulling my spider injection could it be all clogged up its weird because it runs and stays running once it's started

 

Something appears to be clogged or somehow something is wrong in the starting circuit for the injection system.