How about your choke plunger assy on the left side of the carb? I have seen them stick or the o-ring gets wore and allows air to pass causing a vacuum leak and crazy idle issues,last choke plunger kit I got was on ebay for about $35 which included everything.If it's quite with the atv off,work the choke and listen for it to seat "click".Also check your intake boot for cracks,behind it is a o-ring so there are several possibilities,carb cleaner works well for locating vacuum leaks but be careful,don't want a fire
02 Kawasaki 650 -Highlifter module ITP Mudlites HMF/Jetted K&N, 02 Sportsman X 500 HO- lift kit ITP 28" Outlaws K&N, 96 Honda 300 4wd,07 400EX stock for now,93 Yamaha XT350. 06 Eton Viper 90- reeds clutch kit. 79 Camaro -my old drag car in restoration