If you have to close the choke partially to make the engine run "properly"
you have a lean condition, in other words you are not getting enough fuel to the engine.
That is usually plugged passages in the carb/main jet.
That said:
What is engaging a "pot"? do you mean a PTO?
Closing the choke means just that, the butterfly shuts off the flow of air causing more fuel to be pulled from the carb bowl enriching the mixture.
It is normal for an engine to sputter, blow black smoke and run bad when the choke is fully "closed" and some will stop ruining completely.
In order for us to help you, we need proper terms so we are all on the same
page so to speak.
