Cash for Clunkers .
Just kidding. BigDog..you have spent the rent on this problem. The BOAT is not the problem. Your Techs are taking advantage of you. Go back and look at the posts. Just about all the suggestions ...to solve the problem.... can be carried out by YOU....at almost no expense. This problem is NOT complicated. Unlike a computer.....It would be very difficult for you to
Screw it Up....ie Do Damage to the engine or systems.
If this was a
Computer you were fooling around with
in the dark, ....(without a basic knowledge) ...I would say ...You have no choice: LET ..some OTHER/NEW experts look at it...BUT this is a SIMPLE internal combustion engine. THEY replaced everything...............OR DID They.
Take the boat home and look back over this years posts.
I will go back to your earlier numbered list and will eliminate some of the possibilities right off.