Pull off the duct going to te throttle body and see if there is a build up of black stuff. If so clean with some scotch bright and throttle body or carb cleaner and see if it helps. Might not of been closing enough in the warmer weather. That butterfly acts like a choke and regulates air flow. Also easy to do is pull the egr valve and see if it is stopped up with carbon if the throttle body has a bit of black stuff in it and up in the intake.