Edelbrock 1406 carb

[77ChevySharkBite]

Okay fellas I need some help with my carb, over the past couple of months I've been trying to get timing and other things buttoned up and have the truck running smooth, a recent issue I've had with my carb is that is sputters/struggles when you rev it up but when you drive it, it becomes a little harder to drive.

I let it warm up just drove it around the neighborhood. When I try to put any sort of load on the truck it's like it sputters and struggle and you can audible hear it. It will run and you can give it gas but it doesn't run like it should I can tell that. It idles smooth and fine without a beat only when it's revved or driving and trying to give it gas it sputters/struggles and when driving and you try to floor it, it bogs and what I'm lead to believe it backfires. So does anyone have suggestions?

It's a 77 Chevy with a 350 with headers, mufflers, and intake/carb swap done too.