My sportsmen 400 started acting up,The key doesnt shut off the motor,kill switch wont either.I have to turn key off and on a few times.The motor mis fires when the key is off.Also it has reduced power at the top end.It idles fine,any suggestions where I should look

check your wireing, sounds like a short of some kind. or could just be dirt in the switch, try wd40 in the switch hole.