Hi, I have a 2003 arcticat 400 4x4 automatic. My issue is that it will only go to about 25mph then begin to sputter and pop, also makes a clanking sound. I have cleaned the carb 3 times! Had an air leak but i put new hose on. Checked the fuel line, seems to have good flow. It's an automatic but sometime it will shift into gear hard. It does the same thing with the throttle in low and high gear. Im completely lost and have no idea what to do! Thanks for any help!