My 2006 Tohatsu 6HP outboard just isn't running right after not starting it all winter. It starts normal and when I push the choke in it starts to rev pretty high RPMs as the choke is about half way in. When the choke is about 3/4 in the motor will shut off unless I turn the throttle all the way up. I changed the spark plug and I'm using fresh fuel. Any ideas? Thanks!