Clean out the screens up front and watch the radiator screen, too... it can over heat if it gets clogged. Did he give you the manual to look over?
Nice tractor and a great deal. If you search on this forum on the jerky 3 pt. you will find a fix. On mine Kubota replaced the the lift valve to a postion control valve. It is way better. I doubt if you could get Kubota to do anything for you now but you might ask your dealer. Brian