Surging idle on Scag Tiger Cat with 19 hp Kawasaki

Have a 2009 Tiger Cat. Replaced a coil on my mower, new plugs,air filter and blades when finished. Engine now surges. Have never had an issue with it. Had previously cleaned out carb and was running good. Runs ok when cutting and at higher idle but with blades disengaged it surges up and down. Have never messed with any adjustment screws and don't really know where any air or other adjustments points are but will try and down load diagram of carb or governor area to get an idea. Hope it's just minor. Has been a good machine and we clean it up after every cut blowing off deck and air filter, scraping under deck if needed. Any ideas will be a great help. Thanks in advance.

A suggestion--don't blow off the air filter. Air filters provide cleaner air to the engine as they get dirtier.

Surging is usually caused by a lean condition, either by the carb not supplying enough fuel or excess air getting in via vacuum leak(s).