I have a 99 formula III 700 and i;m having mid range problems, Its very slugglish, bogs out until i get the speed up then she takes off. Bottom end is great but then the power cuts right out then picks back up slowly. If I;m crusing along at about 40 or so then crack the throtle, it just bogs out. but when i'm over 60mph and do the same, it takes off. Any suggestions on what may be the problem. Carbs are set at factory settings