sounds like you have not finished the breakin process yet?
I would screw both high and low speed needles all the way in, and then both out 2 turns.
If your idle is to high, adjust the idle set screw (which adjusts the air going in at idle...not the fuel.) There is a sweet spot. As long as your motor isn't revving super high, keep the buggy with it's wheels off the ground so you can tinker with the idle speed to get it right (note, even at a proper idle speed...with wheels off the ground they will be spinning slowly, but the buggy will not move once on the ground)
The idle set screw meets a grove in the carb's slide. It is possible to have the screw in the carb but NOT in the groove. If adjusting the idle screw does not change the carb's opening, then it is not in the groove.