RPM drop and white haze at WOT

[NicksterFL]

So we were out trolling for king fish for about 5 hours. On the way in about 5 miles from the dock I opened up to WOT in the river. Hit 5900 rpms. After about 1 min or so the rpms dropped sputtered a bit then picked up again. i looked back and there was a haze of light white smoke that lingered behind us (not a trail) where we had sputtered. RPMs only dropped to about 5200 and few seconds later we were back to 5900 and I backed down to my cruising speed of 4500.

No other smoke other than that few seconds.

good power and response. Good oil pressure and temp.

Idle was nice and smooth at the dock.

Was that just a puff of carbon?
Maybe VST?
voltage drop?
Water in fuel?

Engine Yamaha 2010 F250

I ran the boat again today and no issues, even at WOT a few times.

 

[NicksterFL]

Nothin'?

 

[dingbat]

The dreaded white haze is typically water in the cylinders. If VST and fuel filter are clean, might want to pull a head to take a peek if it does it again