'80 70hp Evinrude weak spark

[riverrat855]

Need help before buying parts. My symptom is a motor that will run on all 3 cylinders when cold for about 3 minutes. Then it bogs down and I limp back to the dock. I'm definitely getting fuel to all 3 cylinders. Have a good 125psi compression on all 3. Spark test shows #1 good 1/2" spark, but #2 &#3 are weak. [not consistant, [Swapped coils around and symptoms did not change/move. Bought a new power pack but didn't help. Resistance checks on stator and sensor are in line with my Clymers book. Any suggestions?