I have a Troy Bilt mower with a Honda engine. It is a little over two years old. My lawn is less than half an acre large. I have been having some issues with it the latter part of this season. It cuts fine but it clearly doesn't sound good. The sounds it makes is similar to when your running out of gas but that is not the case. I have put a brand new spark plug, and checked the oil. The air filter is clean. I always use a fuel stabilizer in my gas. It was suggested to me to use a engine cleaner such as SeaFoam so I have done so. It seemed to help a little at first but now it sounds worse. I am linking an audio file below.
https://soundcloud.com/ukbsktbll/lawn-mower
https://soundcloud.com/ukbsktbll/lawn-mower