I have a 98 softail, that has started sputtering going down the road after it warms up. It does it at any speed/different gears except 1st and 2nd where rpms stay higher. seem to be associated more with load on the engine/at lower rpms for the gear. I have to drop down a gear then maintain the higher rpms as I shift back up. It also will stall on rare occasion during this... I've had carb rebuilt, plugs seem ok, and I'm lost... Help!