I have twin 135 Black Max, one engine surges at wot/ high rpm of 5300 down to about 4200, then hunts around, sometimes recovers, sometimes when I throttle back and slowly increase, it will maintain about 4500 rpm. I checked the coils, spark plugs, and wires all O.K. Carburators were rebuilt recently, engine runs smooth with no problems otherwise, Left engine runs great and get full rpm.
