2005 Polaris 900 RMK Issue

[Scorpion]

I just took my 2005 Polaris 900 RMK out for a break in spin today (Dec 23/13) and noticed a problem that wasn't there the last time I rode it in March.
It seems to be missing at around 6000RPM but it sounds kind of crackly, not a bog. I just changed the plugs, so could it be the plug gap? (the old plugs looked exact same)
I couldn't seem to get over 50kmh on open stretches and it just seemed like there was no extra power going up hills, there was enough power to get up the hill no problem but not enough to do much else.
I noticed the oxygen sensor has a big wad of tape around it about 6 inches away from the muffler... probable cause also?

This sled was fantastic last year and was great on the last ride in spring 2013 so any ideas of what may have happened between March/2013 and Dec 2013?

 

[catmando]

That's interesting, start with a compression test. I'm asumming no codes flashed?

 

[Scorpion]

I didn't see any codes flash no. I will do a compression test and let you know.
Thanks for the advice

 

[catmando]

If that isn't the problem you may want to check the throttle position sensor,I don't believe it will flash if that's an issue.also there is no code for the throttle body boots.not sure if these will create the issue your having but worth the time to check.another easy one that could possibly be an issue is the fuel filter.