[BarryB]

Remove the engine cowling.
Remove the cover on the air intake so you can see the butterfly valves.
With the engine off, move the throttle to wide open.
See if the butterflys are open all the way.

I once had an outboard that had lost power, the adjustment on the throttle cable had moved and the butterflys on the carbs were not wide open.

Just a thought.

Good luck.