Karting??..

If it's loose in rights and lefts, scoot the rear tires in 1/4" and see if that makes it more to your liking. Towards the center line of kart=tight. Away from center line=loose. That choke lever issue, pull the plug and see if it looks like it was a little on the fat side.
I'm under the understanding that the more you raise the front end the more the rear wheels will stick and the more you lower the front end the looser the rear will get.. so as I move the front tires outwards it will raise the front more as I turn?... And make the rear stick?...