Hello, I have a 2003, Gravely 260z with a 25hp Kawasaki and when I mow lawns that are bumpy the engine will hesitate/ bog out like it's loosing fuel. If I mow at slow speeds it seems fine. I have read some posts about similar situations and have replaced fuel lines in tanks and the fuel filter. I even purchased and installed a electric fuel pump and still have no luck solving this issue. I removed the carburetor fuel bowl and cleaned it out with carb cleaner. I'm not sure whats going on, and I don't want to keep throwing parts at it $$$$$. Any suggestions; or if you have the solution I would be most thankful for your help.