After running maybe 3 minutes at full throttle (2900 rpm in water) my motor loses revs then sputters and dies. Restarts fine, gets back to full throttle OK, then dies again.
Fuel filter is getting fuel. Motor was tuned up this spring by dealer, fitted a Tinytach and replaced carb.

Any suggestions are welcome on what I should check.

Could be your gas hose is getting air or your vent is clogged on your gas tank. What your explaining is some type of fuel problem. If your carb is good check the two things listed above. That same thing will also happen with Old gas or dirty gas.

Try running it at half throttle or 3/4. Mine was doing the same thing and wasn't getting fuel at full throttle. Did the simple thing after fighting it forever and put an e pump on it.

Thanks for your suggestions, I suspected fuel supply may be the issue. BTW in my first note I incorrectly said dealer replaced the carb - in fact it was the fuel pump that was replaced.

JW261 - Yes it runs fine at half throttle, so I can 'get by' until figuring out a cure.
Back at the dock tonight I ran it full throttle, 3550 rpm for 5 minutes, never skipped a beat even when I shook the gas tank.

WhoDat - Tomorrow I will try running a new fuel line from a different tank, with fresh gas, and see if that helps.

Thinking further on why motor ran OK at dock but not on lake. There was a chop on the lake so we were bouncing. Fuel tank was maybe one third full, so I wonder if motor was sucking in air or froth. Will try a full tank. If that cures it then I guess I need an electric fuel pump as Jw261 suggests.

if your handy at all you can do an electric fuel pump on your own its pretty easy

I had the same prob with my 16 vanguard. I tried everything. New everything from the tank to the carb including the pump. Could not fix it. I replaced it with a 20 honda and hooked up the old tank/line/bulb and it has never skipped a beat.
Good luck and let us know if you figure it out. Nothing worse than pumping the bulb every 30 seconds.

Fitted e-fuel pump. Seems like motor gets enough fuel now, though it did slow down and die once yesterday. When I checked engine the choke was half on so that may have been cause.
At WOT getting 2830rpm in water, boat was doing 15 mph with 2 people plus fuel and battery. Sounds like this is about right for this motor and boat combo.
Only problem now is strong torque steer to right at WOT. Also at WOT cav plate will suddenly rise out of water, rpm rise to 3150, and steering is nearly impossible. Am buying the biggest crescent wrench I can find and will bend back of cav plate and prop guard to try correcting next week. Will report results.