Also check that the intake is not sucking air after warm up. Common on a 235.spray some carb cleaner around the intake to head and around the carb base. CAUTION this can produce fire so dont use a whole can. Maybe retorque the intake(most times if its leaking its to late) I have also seen about 3 -4 warped 235 intakes that i had to cut.Check the carb gasket also and make sure the carb is tight.