Sp: You certainly have a fuel restriction . If you can blow through the fuel filter you can rule that out . Having soaked the carb in concentrated fuel cleaner is a start. Next you will have to thoroughly clean the fuel circuits . Removal of the Hi & Low Speed Jets and either inserting a tag wire or blowing (compressed air) will ensure all varnish or gum has been removed. Another final spray of carb cleaner prior to jet replacement will also help dislodge any residual debris. Add some carb cleaner within the fresh fuel and restart the mower and let it run until it will idle and full throttle response is restored . In the future ensure to use a fuel stabilizer and fuel cleaner upon seasonal storage and start up . You should not require fuel pump replacement .