i`m new to this forum and hope someone can help i have a 1987 wellcraft 192 classic with a 140hp 3.0,when i`m in gear it doesn`t seem to rev past 1000 rpm,my top speed is 10 knots and it won`t plane out,but whilei`m in neutral it revs as high as i want it to, it also makes a rattle noise in gear when reving past 800 rpm,i`m thinking i have the wrong prop but not sure the prop on it now is a 15 1/2x21 any help would be appreciated thanx in advance