Hello, I have a questioned for the seasoned professionals

I own a 1971 Jimmy with a 350 engine and some aftermarket edlebock carb

The engine idles fine but here is my problem

From a stop if I push the gas too much the engine kind of stalls for a bit then catches up with itself and runs fine

also let’s say I'm doing 40 mph and I push the gas a little more to gain some speed- the engine will start to pop lake crazy kind of like it backfires but if I stomp it to the floor the engine goes and performs like normal... Any ideas as to what could be causing this?

Thanks

 

It sounds like the carb is probably running lean. Try opening the air fuel mixture screws 1/2 a turn each and see if that makes a difference.