won't turn off

mine done the same thing after i washed it. i have a kill switch mounter on my front plastics and i went mudding, then took it to the car wash, and i started it up and road it around the lot a couple of times to blow water out of the exhaust. then i went to park it and everytime i flipped the kill switch it wouldnt do anything. so i just popped the clutch
 
Engine runs good now with new crank seals and white smoke is gone.I'm still having the super high revs when running out of fuel.When this happens the key and kill switch will not kill engine.But when there's fuel in tank it runs great and turns off as it should.I'm thinking air leak or carb problem. I do use a after market carb(pwk) not sure what size.