Hi, Jerry . It sounds like a ignition problem. I will list the problems that I have found working on motorcycles and outboards and sterndrives. When I first got my 1950 Ariel Square. 4, when I came to a stop it would stall or stay at 2500 rpm. I found that the distributor bushings were worn out.( I could change the point gap about .040 pushing back and forth on the distributor shaft, normal point setting .018 ), On a 3L OMC ( Big ford pinto engine) it would run fine then lose power or stop, we found that the roll pin that held the gear on the bottom of the distributer shaft had sheared. On Kawasaki 4 cylinder bikes, (650, 750,900,1000,cc )customers would try to turn the motor over with out removing the spark plugs and shear off the drive pin for the point cam. I would also check the drive pin for the points cam or the trigger if eletronic ign. Have Fun, Brian
