My bike ('06 450) seems to be missing or stumbling when I'm cruising it at a constant speed. Throttle is between 1/8 and 1/4 open. Pilot jet is a 42, Main is a 155. It does it whether I'm at 4500 or 6000 ft in elevation. The last two rides have been in cooler weather (75 F) and it has seemed a bit worse but it may be that I'm just getting more iritated with it. I've played with fuel mixture screw from 1 to 3 turns out with no help. I've tried the needle clip in the 3rd, 4th and 5th groove without much difference and I've cleaned the air filter without much improvement. Where do I go from here or what have I missed?