last spring my 06 sb,was cutting out after half hour or so. it would rev to 7400, when pulling hard up a hill it would drop down to 3500 rpm. let off the throttle and feather it and it would go back to7400 rpm for a while. then do it all over again. if you stoped for half hour it would be good again . tried fuel filter, tps adjustment, checked tps wires, any thing else to check clutching is new and clean. possible stator?