86"pontiac6000,have fuel issues,changed pump,fuze,coldstart valve,wht could it be?turns over,sometimes starts but soon dies,where do i go from here?

Optional Information: 1986 Pontiac 6000 2.5
Already Tried:
changed fuel pump,cold start valve,checked fuse,checked filters...sometimes the fuel comes threw the carb. an others not,it turns over but more so when cold it will start an run,but dies within 5minutes of drivin