1985 Jeep CJ7 Engine bucks and kick at full throttle

I put a chevy 350 in my Jeep CJ7, with a Rochester 4 bbl, and headers. It runs very well except for one problem. When traveling between 25 -35 mph and I floor the accelerator the engine will buck and sputter to the point that it feels like it will die...or give me whiplash. However, if i let of the throttle a tad it will resume the acceleration...at a less aggressive manner though. The engine has about 20k and i just put a new Rochester carb on and the new one does the same thing. On rare occasions it will sputter and buck with moderate acceleration. It performs very well with the exception of the sputtering.

Thanks Jim