holley help please 750 vac.

ok car not running for a while 750 on 340 satrted car runs back fires up through carb at quik exl.1 took out old gas no change 2.cahanged out power valve no change 3. changed out exclr. valve under bowl 4.shooter is a 31 6. checked timing 5 6.pulled plugs there good little rich but ok checked wires there correct place it seems to suck back air under some what smoth but fast exl. then kinda studders thatn may back fire through carb any help please any one pleaseee...:read2: