88 Marathon 2 Cycle won't run correctly at low speeds

[ITA47]

I have a 1988 EZ-GO Marathon 2 Cycle that I recently bought and I can't get it to run correctly at slower speeds. The engine has 110psi compression and starts very easily. It runs really good from about 1/2 throttle to full throttle, but if you try to drive it slower from closed throttle to about 1/2 throttle the engine cuts out, making the cart jerky. I had a problem with the fuel pump not working so I took it apart and cleaned it and it is working great you can see full fuel flow as soon as the engine starts turning over. I have pulled the carb off twice and cleaned it with carb spray and the second time I pulled the carb apart and soaked it for 30 min. in Berryman's Carb Dip, then sprayed it down with carb spray and washed in out with water. Then I used my air compressor and blew it out and put it back together and it is still doing the same thing. Has anyone else had this type of problem with their 2 cycle? If so what did you do to fix it?