can't get smooth idle on 78 evinrude 70 hp

[ing]

I have a 1978 70 hp model 70873c outboard. I have rebuilt the carbs. changed the fuel pump and replaced all three coils. Each one of these has helped to smooth the idle a bit as well as at higher rpms. I still have an inconsistent miss and the motor sounds as if it surges after it misses. It will run really smooth for 20 or 30 seconds and then miss a time or two sometime a lot and smooth back out for another 20 to 30 seconds. this miss is a rather hard miss and will cause a good puff of smoke. I am not sure what to try next. Any help would be greatly appreciated. Thanks

 

[Daviet]

Re: can't get smooth idle on 78 evinrude 70 hp

Are the idle orifices all the same size and are they clean and tight? Are all of the throttle plates completely closed at an idle? When you overhauled the carbs did you remove the core plugs on top of the carbs and clean the tiny passages underneith the core plug?