84 Nissan pickup why would it pop or sputter?

It could be a intake or exhaust manifold leak.Dirty fuel filter,check air filter,check vacuum lines,check charcoal canister filter,its on bottom,just remove from spring and tilt up .it cost 2.00 at auto zone,check catalac converter,have you been having carb. problems,Ihave 85 with z24 engine,Ireplaced carb. with a weber 32/36 carb. kit,you can chech them out at weber direct.com,but you have to get carb. kit,it will change your vacuum lines and eliminate a lot of valves and you will plug some outlets too,they don't give you a diagram for the changes,but if you decide to get one ,I will show you a diagram,go to you tube and look up 85 Nissan 4x4 silverbullet and check out my video,if you can leave a comment,thanks,tom