I have a 1980 berlinetta with a 305 and rochester quadrajet carb, the car runs great at half throttle and down but when i floor it it missfires and won't pick up power, have had it on the road for a month with no issues until now, any ideas?

 

Could be a lot of things but the first thing I'd check is the choke, sometimes they will close when they aren't supposed to.
You might even get it to do it in neutral with the air cleaner off while you look at it.
You could wire it open and drive the car to see if the problem goes away, if it does that confirms a choke issue.
Might be a partially plugged fuel filter at the inlet on the carb, I'd for sure change that out anyway if you haven't.
Could be time for a carb rebuild, accelerator pump might be shot.