Carb rebuilt, engine still hesitates.

Well, you need to determine if it behaves as if it is running out of fuel.

Running low on fuel (lean) will typically loose power and have a moaning whoosh engine sound while pulling hills / under load. Sometimes it can buck and hiccup but first it will just sound like it is loosing power.

The problem with diagnosing something with out test equipment is you really need to be able to feel and hear the problems.

Determine if the issue is related to load or simply rpm or both.

If you can, take 3 videos from inside the car with the windows up with someone else operating the camera.

Trigger the issue by driving along slowly and then steadily mildly accelerate up a long hill. Try other scenarios to cause the symptoms and describe the test scenario at the end of each video so people on this forum can hear and observe the behavior based on the test environment.