I have never heard that a to small carb. will make the motor surge
They usually will run better with a bigger carb
Surging, running out of fuel, and hopping are two completely different issues Figuring out what the car is doing is the key to fixing it
I would try and have someone video a run from the side at a 90 degree angle on the starting line as close as they can get to see what the chassis is doing the first 50 to 100 Ft.