Ignition Issue????

Ok, ive had this problem for a while and i think im getting it narrowed down. ive got a 360 with 800 Double Pumper, comp cam, J heads with 2.02 valves, ect....let me know if you need more on my engine. My car takes off great, up untill about 4k to 4500 RPM. then it revs slowly, spits and sputters, sometimes you can make it to 6k rpm(very slowly) and sometimes you can only make it to 5k rpm??? Its NOT the carburator, (ivehad 3 different carbs on it that were tuned/adjusted while on the running motor and always still had the same problem). Its not the fuel pump (thanks Rumblefish360). When you shift into the next gear it starts to rev insantly(no waiting for fuel to come) util 4k rpm of course. I just tried another ignition box with no luck. It could be the distributer but ive got brand new rotating cup, cap, vacum advance on it. So what do i have left as an option? Coil? Im pretty sure its an ignition problem somewhere but i just cant figure it out. any help?