1991 200hp xp evinrude

[grobbin]

I have a evinrude 200xp that doing a weird thing . It has enough hp to get on plain with me and a full load of fuel but add another person and Boggs down until I stop and shake the main wiring harness . Then will go on plain but can still hear it miss. Happens every time I stop and fish for a hour or longer. It has new powerpack and timing base new plugs checked fuel system no failures.