Engine surges or cuts out 90 HP 4 Stroke Yamaha outboard 2012

I have a 2012 Bennington Pontoon boat with a 90 HP 4 Stroke Yamaha outboard. I have 22 hours on the boat. At about 14 hours when running wot or above 4600 rpms the engine will intermittently and without notice drop from 5000 rpms to approximately 2500, back to 5000 and back to 2500. If you throttle back to 3500, all is well. If you don't throttle back it will bounce back and forth until engine goes to just an idle. I feel problem is electronic, due to it's speratic nature. It also seems to happen after you have been boating 20 minutes or more. So, I think heat is a factor. I know the engine and boat are under warranty, however I'm concerned about dealer having boat and being unable to duplicate concern. Local dealer is not located on the water, so they are limited to testing with water hose. I'm hoping someone has experienced this concern before and can help me help the dealer. Thank you.

Hey I have a 08 model same engine that is doing the same thing... Did u find your problem? Thanks