Slimmy my boy,
Hard to believe, but I think you have a Tohatsu. If I'm not mistaken, it's  
made by Yamaha for both Tohatsu and Mercury.
Sounds like you have a mismatched prop. I don't know what I currently have,  
but Rum Runner is coming out of the water for buffing and waxing this weekend. 
 I'll probably change the foot oil as well. I'll get the prop number and let 
you  know what I have.
 
Rummy