i have a 1989 30 hp johnson it runs great till it warms up then it starts missing, runs like on 1 cilender. i have changed out boath coils,stator.power pack,high voltage coil,new plugs.fuel pump,carb kit,still does it . any ideas.
Welcome aboard, crodad.
I have the same motor.
Sounds like you changed everything I can think of.
Sometimes knowing the history of the motor helps to troubleshoot.
Is this a "new to you" motor? Did it run well before?
Do you notice the miss at idle, high speed or both?
Is it the SLOW function kicking in?
Do a test by disconnect the temp switch in the head that goes to the power pack.
If that helps, either the engine gets hot, switch is defective or you may need to replace the water deflectors in the cylinder to correct circulation.