So it never did that until you installed the carb. right?
So we can rule out any other component than the carb. When you say 3/4 throttle you mean the pedal is almost to the floor?
More info like RPM's would help
You might be running out of fuel but if you don't have a pressure gauge hooked up we can't tell that either
More info please
Gus


64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60