Carb problem

Slowly getting the bugs worked out of this car. Now the carburetor. It is a two barrel holley, 2300series. The car warms up and idles great. As soon as I give it some throttle it starts to die, I have to feather the throttle to keep it going. When I give it most of the throttle there is a lot of power but I can feel some surging. I have rebuilt the carb with a holley kit. Anyone have any ideas? The only thing other than the rebuild kit that was added was a power valve protector( backfire protection).