what kind of choke is it? if it is a heat coil type you may need to adjust the coil. if it is an electric, throw it away. if it is manual, just play with it. my 235 isn't rebuilt and it skips or hesitates at about 70 mph just a little. it used to do it real bad until i got the dwell set correctly. also the electric fuel pump may be part of the problem. i tried one with very little success, my 235 liked the manual pump much more.
