I was having an issue with my 2007 400ex cutting out after high speed passes and when letting off throttle. Took it to a shop for repairs and the valves were adj, carb cleaned, and replaced/repaired header screw bolts. Now the quad has a lot more throttle response but it won’t idle. The repair guys said it can be bc of the k&n air filter lid and advised I should get the stock lid bc it’s letting in too much air. What do u guys think? I never had this issue before, but also this is my first winter with the quad and it’s about 30deg. It won’t stall after riding now, but still is not idling unless occasionally giving it gas.