Do you get "proper" WOT action for a bit then it drops 1k after X secconds / minutes use? If it's going into a "limp home" mode, it could be any one of your sensors are going in the huff or loosing contact. My only reservation about that thought is that if this is the case, I would have thought a far more spectacular drop in revs would be seen..... Unless Yam have been especially clever with their emmissions protection?
Probably worth checking every 'leccy connector under the lid - unplugging & replugging is usually enough to scrape off any cr@p on the contacts. Then reassemble with your favourite water dispersing fluid!
Most ECU faults (in cars anyway) will self clear if the problem isn't detected continuously / regularly, otherwise engine warning lights would become disco lights on the dash! Mind you, if you were out with the laptop plugged in, any fault code I would have thought would be flagged up even momentarily.
It's moments like this that old two- strokes have a certain appeal!