Hello gents, my first post, great forum BTW. My 2007 Yamaha 70TLR on a 21' pontoon will not reach WOT. When I push throttle full, get's to 5k then shuts back. @ 3/4 -5/8 throttle, runs right @ 5k. Manufacturer states 55k-6k is WOT. I have 14"x13" prop. Checked around to see if going to 11" pitch...