360 magnum troubles

I rebuilt a 360 magnum and threw it in my Dart, but I can't get the damn thing running right. This is my first engine build and after a ton of problems, I finally got it to idle. The new problem arises when I apply any throttle. I can get it to start up and idle; but when i give it any throttle, it sputters, dies, and coughs out of the carb. Anybody had similar issues and have some sage like wisdom to share?

here are my specs:
Junkyard 360m bored .030 with stock bottom end
Keith black pistons
Custom ground cam on old core
Engine quest heads
Edelbrock RPM air gap
Holley 750 double pumper (recently gone through, maybe i'll do it again just to be sure)
Doug thorley headers