Throttle bog..

Obviously learning as I go. Posted on Facebook with minimal results. I have a slant six that’s stock. I have been having an issue when I put my foot to the floor it stalls and won’t accelerate. When it’s about 80% -1% pressed it zooms on along. When at 80% and I slowly release the throttle it stumbles but accelerates all the way as my foot goes back to 1% off the throttle my I have tried adjusted valves, new plugs, wires, rotor, cap and played with timing and mixture screws the best I understand. The fuel tank and filters are clean. Fuel pump fills the carb an filter without issue. It idles good and starts good. I have had this issue since day 1 over a year of owning this car. This is my only issue any thoughts? Carb float has been changed and raised, Carb gone through, new plugs wires, distributor works new vacuum pod..