2020 Pro XS rpm surge

[Elf]

New member and need the knowledge of this community.
Have 2020 200hp Pro XS. 57 hours. Only run ethanol free gas. I keep the tank topped off and boat is stored inside.
Boat has an rpm surge through entire rpm range. Idle set at 600 rpm. Rpm drops to 580 and goes up to 620 on about a 15-20 second cycle.
Same thing for all rpm ranges on plane. Drops about 80 rpm and surges about 150 from steady throttle setting.
Water in gas has not been indicated.
Changed fuel filter. No indication of water.
Cranking battery load tested and good.
Vessel view indicates no faults.
Dealer laptop indicated no faults.
Will pull and check plugs next.
Any ideas after that?
Hate to pay shop labor rate for troubleshooting.
Thanks in advance.

 

[CincyGus]

Could be Adaptive Speed Control. Adaptive Speed Control maintains a desired rpm regardless of changes in load or conditions without adjustments to the throttle lever position – a first for the outboard industry. I'd check spark plugs as you mentioned as that sounds just as likely.

 

[Elf]

No. This one was just the fuel demand valve. Easy fix, but really surprised it went bad with so few hours.