So I've been having some problems with my '08 300xcw fouling plugs. I went ahead and took the carb out this weekend, put in a leaner (165 to 162) main jet and moved the clip on the needle up one position. So I rode it around the block a few times and it seemed to run fine. When I got it back in the garage, I blipped it a few times, when suddenly the rpm's stayed high even though I closed the throttle. I quickly hit the kill switch to turn it off. I took the top of the carb again, and made sure everything looked good. The throttle seems to open fine, and then snap closed like it should. I started it back up, and it was idling normal for a few seconds... Then it started buildig rpms up on its own w/out me touching the throttle and I had to shut it down again. Any ideas??