On my Mercury 9.8 I was having a problem at high throttle the prop only spun like you were trolling. Not fast at all. People gave me some suggestions and I checked them all out. After reading a post that laddies replied to I started thinking. Here what it was, the reverse lock out rod and ball wasn't locked into the small socket. It was bent out on the oppisite side. I connected it where it belongs and wulaaaaaa, it worked great. Full throttle and no slipping. Thanks for all the help people.