1989 GMC S15 Sierra Classic 4x4

the truck has a 4.3 6 cylinder. air,crusie,power windows. all works except the air. it starts but dies out or runs rough. I am thinking it is a fuel pump or filter but dont want to mess with it. it's been parked in the barn for 2-3 yrs. will need to be towed or trailered. make an offer and get it out of here. if I need to lower the price anymore I will take the time to get it running myself and sell it accordingly