Jack it up and spin it in 2 wheel drive.If it's ok ,then put it in 4 wheel drive.Block it up good and be careful.This is how i found my problem.

 

Did you check tires did you put slim in them or are the rims bent bad just throwing out a suggestion . As far as your engine it seems odd to me that it would just start acting bad did you check fuel filter or check for bad gas maybe . Hope you get her working right

 

I have slime in my tires and didn't have any problems after I put that in. My rims don't have any dents, just some scuffs. I replaced my fuel filter when I did my last oil change and I added some octane boost to my gas cuz it had been sitting for about a month. I will have to see if this airbox mod fixes the problem. The idle has never seemed to be right. When I adjust it and it seems good, the next day it is low again? I wondering if I may have found the vibration problem. Remember how I said I didn't have it until I put the chain tensionor on, well I ran into a problem with the spacer that cam with it. It put the roller too far out so that the chain was partially off the roller. So, I ground the spacer down some, but I couldn't get it down far enough to where I needed it. So I used some washers for a spacer. Then, I ran into a problem with the chain hitting the spring bolt. So, I had to use some spacers to space the tensionor itself a little farther away from the swingarm. Then I put the old spacer back on. However, I think that the old spacer is a little crocked (sp?) from the grinding and may be causing the vibration when I am going fast. Does this sound logical?

 

Anything could be possible for the vibration I suppose it will just be a trial and error thing .
My scram never idled right either then i put in the dynojet kit and it idles like a charm now so I guess it could be your needle like someone else had said