1985 Yamaha V6 Special not firing on all cylinders

I have a 1985 Yamaha V6 Special which I have done a lot of work on and still cannot get it to fire on all cylinders. It had a lot of corrosion on it so I have cleaned it up. The carbs are cleaned. Changed the spark plugs. Put on a new coil. Compression is good. Changed the stator. When I changed the stator it actually ran well for a minute then went back to not firing on all cylinders. ANY help on where to look next would be greatly appreciated.

[boats.net]

Test all ignition componets per service manual. Make sure all ground wire connections are good.