Problem with 2006 STX

[megabiteman]

Alright to start this off, I am not the mechanical genius. In fact I'm VERY amateur, keep that in mind when trying to explain things to me. Thanks!

That said:
At the end of the last season we decided, instead of paying to have our local marina winterize and store it for us, we could winterize it and store it in our cottage's garage. So we took the oil out, took the battery out, and put stabilizers in the gas. A few weeks ago we first got it out. We took it and topped of the gas, put in oil, and put the battery back in. When we got it in the water it started reasonably well, however it felt like there was more vibration than I remembered it having, I'm still not sure if this was imaginary or not. Anyways I took it for a small lap at about 30 and it felt fine. Then I decided to start giving it more gas. While I worked my way up to full throttle it seemed reluctant, but I assumed it was just warming up. I took it in, not sure whether or not to be concerned. We came back a few weeks in row to find it still giving us problems. It had really odd acceleration, like if you were to try going full throttle from idle, it would only give you like 30mph instead of the usual 55ish, then suddenly jump up to full power. It would also randomly lose RPMs , especially on turns where it felt like either the transmission or throttle was having problems. It also died on us while we were riding and at idle.

Without a chance to really investigate thoroughly (like I would be able to figure out what was wrong) my dad decided to buy new sparks for. I have no idea whether or not they'll help.

Any advice?
Do you think its something we did wrong in winterizing it? Has it just taken four weekends to warm up? Is it throttle or transmission? Something completely different? Whatever you think it is, what can I do to help/fix it completely, without needing to get it serviced?
A reply by Friday or Saturday would be hugely appreciated! (That's when we go up next and plan on putting the sparks in) THANK YOU SO MUCH!

[Jeff Walkowiak]

usually it is old fuel that makes them run like crap,, stabil or not I don't like leaving fuel sit more than 3 months,, it is probably going to clear up as you add new fuel try some premium fuel to get the octane up

[tizzam]

plugs, mine did the same thing. put new ones in and fixed the issue. make sure you put some neverseize on the threads uncles #1 snapped when removed had to take the head off to fix