i have a 1978 4 hp johnson outboard (4w78e) ran great for the 4 or 5 times i ran it. it was recently rebuilt when i bought it. started running rough when going from full speed to lower speed then stalled and would not even slightly fire again. there is no spark now, i did replace spark plugs and still nothing. checked all connections and coils look brand new. the only thing i can see that is worn is the sensor assembly. is there any advice or anything else that may be causing this problem? thanks in advance! also i did attempt to test the coils from spark plug wire to coils and both had the same reading.