1989 85 Force OB. Never given me one hiccup since new. Regularly maintained, sort of. Idled all morning Sat in a wind condition on a lake sort of a shakedown morning. Hit the gas to run her home, power came up as norm, vessel planed as always, ran on top for 30 seconds or so, and the RPM dropped til she stalled. Waited 10 seconds while searching the obvious, hit the key, fired right up. Let it idle a little while, purred like a kitten, hit the WOT, same as before; all good for 30 seconds. Idled it in. Any ideas? I'd hate to have to use Seatow first trip out.

Clogged high end jet in carbs
Carb cleaner

sounds like a fuel delivery issue.
clogged vent, bad ball, fuel pump{s} shot.?
basicly running out of fuel, fuel system can't keep up with demand.

I had an 87 merc with the exact same symptoms and after checking out everything that had to do with fuel I still had the problem. I took it to a mechanic and he found that 1 of the power pacs ( 2 in that engine) was cutting out at high speed. He replaced it and problem solved. I would still start with the fuel system - simple things first.

Cloged Filter, Vents clear, ball not holding??

This new gas can cause filter clogs for the first few tanks, I had a problem like that last year. But if you have used a few tanks of it you should be fine.

check for scamooge in carb bowls.

scamooge is a very technical term from gunk, right?

gunk and/or debris- motor is 17 yo. would'nt hurt to clean 'em. had the very same problem with a newer motor.

Definately a fuel problem.

Thanks guys. As I figured she is simply running out of fuel. Obtaining a fuel pump kit and will start there. Keep you posted as to what I find.