WOT for my 2004 Yamaha 90hp 2 stroke on my 19ft flat bottom skiff is around 4,300 rpm's. I just read that it should be between 4,500 and 5,500. What does it mean that mine is lower? Is it the wrong prop? It does seem to use more gas than I anticipated, are these issues connected? How do I figure out what prop I have on there and what one I should try? Or is it another issue all together?