After being out about 40 min, running at speed to get out and then at a slow speed, went back on plane and the motor died. Restarted and ran at slow speed, then back on plane, motor dropped again and I brought to idle. We idled awhile and then went back to speed and was okay. Tried it a couple of times up and down, it did it once more but a couple times seemed okay. When the motor started cutting out it sounded like it was flooding or gas had some moisture or the mixture was bad, it was a sputtering gasping kind of sound. Did not keep trying as the wind was coming up and we headed back to shore.
It is a Mercury 90 4 stroke.

Any ideas where to look??

your post brings back memories, not fond ones either.

Are you using fuel w/ ethanol? I had similar problems last year and after lots of attempts to fix, found there were actually small pieces of rubber (from fuel lines) trapped in the carburetor. They would, at times, block the flow of fuel. After idling or shutting down, pressure would release them and all would seem fine, 'til they were sucked up again.
Had to replace everything in the fuel system but haven't had a problem since.
BTW, I only use gas without ethanol now! Costs a little more but definitely worth the money!

I have just put one tank in and barely used that, I don't know what the previous owners have used but I did use an ethanol fuel and added the sta-bil.
I haven't probably put 3 hours on the motor myself and have it out only three times, with the third time is when the problems started, have only had the boat for three weeks.
What you said "CaptJack_1" makes a lot of sense, have to get it checked out, I suppose.
Haven't found any ethanol free stations close by a few that were marked on the map are no longer.
Thanks..

The few times I've trailered in-state, I've used this list to find ethanol-free gas. Most of the stations I tried were good. I don't know where you're located, but check this link. There may be one near you or on your way to the launch ramp.
Hope you get it figured out. I know it made me nuts for about three weeks 'til someone came over at the ramp and told me he had similar problems w/ fuel lines, etc.

pure-gas.org/index.jsp?printable&nocopy=true&stateprov=FL

Make sure all fuel lines are nice and tight with no leaks.

FJ, from what I have read, ethanol and some older fuel lines are incompatible. So like Capt Jack says you may have some crap from your fuel lines in your carbs. from the previous owners use of ethanol laced fuel. BBR has a good point as well. If you have any loose fittings in the fuel lines, the engine is going to suck air in and mess up the final air/fuel mix delivered to the cylinders.

Might want to check the fuel filter also.

Thanks all,
It is in the shop, I will let you know what it was, if they find it...

I had a problem with my the inner lining of my fuel collasping at high rpm. Back it off and the motor would run fine. The problem was between the primer and motor. Replaced all fuel lines and motor runs fine.

And the answer was: Clogged filter - we shall see !!

I always check the filters first especially if you have and external fuel tank that you fill up and plug in to the engine or if internal fuel tank is old,,, check your filter first..just my routine...F.A.S.T. Fuel, Air, Spark, Timing is what i learned in gas engines in school...