My son has a 99 900, was riding it shortly after he bought it and it started acting like it ran out of gas. Wasn't below half tank, filled it though and it straightened out. Since then, there would be an intermittent miss below 5000 rpm, it was still there at higher rpms but barely noticable. We took the tank off and when we pulled vac tube, one drop of gas came out. EUREKA! We thought found the problem, ordered and replaced diaphram, rna worse. Found sediment and crap in tank while we had it off, so we though something ran into the carbs. No sweat, pullled carbs, removed bowls, littel sediment, enough that MAYBE clogged a pilot jet, os we cleaned all the jets, reinstalled everything and it has a horrible miss now, like one cylinder is dead. (Below 5000, then it seems to pick up). SO HEEELPPP, before I launch it into our pond!!!