Help!Truck won't start

[rusted75 half ton]

Hi,it started last week it stalled out a few times the finnally died,ans couldn't get it stated.It'll crank but won't fire off,a few times I can get it stated but it dies quikly.Sofar I checked the easiest problems,made sure there was gas in the tank!!and replaced the fuel filter.When it sits gas is making it's way up to the carb inlet.The truck is stock with a 396,stock intake and a chevy Q-jet carb.I don't know much about carbs so not sure what to look for.any help is appreciated