Ok, I have a 03 ZL 600 EFI. My sled seem's to run fine at lower speed's and up to half throtle after half there is no more power,make's noise but won't go any faster. I have been haveing to clean my APV's like every 300 mile's, this time I cleaned ran good for about 100 mile's,tryed trail side cleaning after started looseing power but didn't help. Put new plug's in and that didn't do much. Now from ideal to wide open the engine seem's to have a miss/viberation. When your rideing at any speed the engine isn't running smoth,it seem's like miss/shurdering. This is the kind of feeling when a carb's are WAY out of sync or you have a fouled plug on a tripple. Now my sed would run 100+ mph up till the middle of last ninght,it seemed to progressily get worse and now it's a whole 80 mph wide open on a icey road. Ever since I bought this sled the power seem's to have been eratic and come and go. If I let my sled sit and cool off for a little bit and restart sled power seem's to be much better but quickly seem's to go away,I have checked and sled isn't over heating. I was wondering if the sled could be in limp mode. THE other issue that happened last night is my gas milage has gone to hell,like cut in half. My budy had my other sled out with me and they both use about the same amount of fuel untill last night,I used more than twice what he did and he could ride faster(skidoo 503 fan) this just isn't right. PLEASE HELP,I am haveing nothing but problem's my this Cat and don't know what to do.