[bigdog]

OK Forum members, I believe I have identified and fixed my problem.

DRUM ROLL PLEASE !!!! Coil ! No @*^$(*@#$(#&%# Coil !

Yup, I believe this was the underlying issue. Knock on wood !
Many thanks to the following who indicated that this could be the problem:
JRC
NOBOZO
robmac
BroadHopper
Maxum

Although, I believe the 'Ignition Module' I suspect was a contributing factor, being the open circuit board was corroded and rusted electrical wires like threads!

Replaced the Coil shortly after my last thread reply, last week in July.
Have made about 6 boat outings with the family without any engine issues as previously described: coughing, backfiring, stalling

Each outing lasting 1-2 hours of actual engine running time. Engine running at different speeds from wake-speed to full throttle.

Several folks indicated that when the coil is COLD it works fine, but when it heats up,it may be shorting itself out. When engine cooled down it would run fine again. I believe this is exactly what was happening, because this was the exact circumstances.

Also been adding fresh 89 Octane after each boating trip, keeping the tank full. Added Startron to tank, following product mfg. instructions.

So far so good. Hopefully, the problem appears to be now a mute issue.
I will take a picture of Coil to upload and Post. Rusted on outside of body, and inside of terminal tower looked corroded !

Thanks again for everyone input, greatly appreciated !

Bigdog