1989 EZGO, no power midrange

[Hazmat1234]

Just acquired a 1989 GX444 with the 2pg motor. The motor starts and runs but seems to be bogging down and not getting to full rpm. What I have done.
The drive belt is off so I know it's not the clutch holding it back. The carburetor, fuel pump and spark plug has been replaced. (Had the same symptoms with the old parts prior to replacing) The fuel tank was drained and new fuel. Muffler taken off and "cooked" clean. With the muffler off, it doesn't bog as bad or not at all. After burning the muffler the problem is still there, but not as bad prior to burning.If I either move the choke on and off really quick or restrict a little air flow it will get past the bog and go full throttle. Once it gets past the bog it will stay at medium to full throttle. Once the motor gets to low rpm or stop, the problem is there trying to go full throttle again? I'm lost on this one?