If it is a 2 speed, the transmission may have too much transmission fluid in it. It is easy to ovefill 2 speed Puch trannys because the fill plug is on top of the tranny.
You can drain it (drain hex head nut under the rear of the engine (tranny). Refill it with 9.5 ounces of ATF type "F".
Second thing, the idle issue. sounds like you have a vaccum leak around the engine to intake manifold connection or the carb to intake manifold connection. It's sucking in extra air making you run lean and Hot. Make sure all the screws and bolts associated with the carb are tight (but don't overtighten).