"(Took it to the dealer and all they did was wiggle the wires, cleared the code and charged me $250.)"
Yeah, I just had a 45 minute conversation with Greg Clower about this kind of thing.
Good to hear you got it working.
The things we were told to do when a boat came in for service were:
1) Verify the complaint. If it's not verified, it can't be found.
2) Do a visual inspection. Some things are there to be seen.
3) If it's electrical, do a wiggle test. Sometimes this will cause/cure a problem, even if it's just temporary.
4) Verify that the work done actually fixed it. Sometimes, this is not done and an intermittent problem will show up again.