That would be my first attempt also. It worked on my Wards 2000 that surged like that for three years and no other cleaner would do a bit of good. Added about 4X the stated amount and ran it hard for several hours. Started making that part of my opening season breakin for all my small engines after that.
Most likely it is a partially clogged passage in the carb.
If it operates correctly under different types of load (light load, medium load and heavy load) but only has an issue at no load it is most likely not the governor.