Choochoo, I have a neighbor that has a smaller optimax on a pontoon boat. Summer before last he had similar problems. Turned out the liner inside of the fuel line was coming apart and small pieces of the liner was causing the fuel problem , the tank was full of the junk. We pulled his belly tank out and I gave him a tank that was in my Carolina skiff. He replaced all the fuel lines and cleaned the strainer/filters and he was good to go. This may not be your problem but something to cheak on.
This is a great catch. Your 2007 was built before the new, ethanol resistant hoses came out. If the factory hoses haven't been replaced on your motor this could be the culprit. The goo that comes from the break-down of the hoses settles in the bottom of the tank. That's also where the fuel is drawn from. You're doing great at idle because the boat is on plane. When you try to power up the boat tilts, perhaps causing the junk to interrupt/impede the draw of fuel from the tank. Just a thought.