I have a 1989 150 hp suzuki outboard that is giving me a little
trouble I have not been able to figure out.

Last year when running, the engine bogged down and died. I could not
keep it running faster than about 1200 rpm. I replaced the plugs
which did not help, and then I replaced the fuel filter and all worked
well. I have a spin on fuel filter / water seperator in the fuel line
before the engine. The engine did not idle very well.

At the end of the season I rebuilt the carborators and it idled much
better and continued to run well.

This past weekend, we ran 40 minutes to our fishing hole, fished for
1/2 an hour and started up to move to a new spot and as soon as I got
on top, it started missing. The further I went the worse it got. I
pulled out my spare filter & replaced it on the water. This did not
help at all. We slowly made it in and the next day I found the primer
bulb was defective. The check ball had come loose & would check the
line in the flow directed. I replaced the line thinking this would
correct the problem. We went riding for about 1-1/2 hours with no
problem. Came back to the landing, worked on the boat trailer for a
while and then went back out to run it some more. As soon as I got on
top it started missing again.

If I chocked it a little it would stop missing. I ran like that for a
few minutes. The engine bogged down real bad and then started running
normal. It did not fail for the next 1/2 hour back to the landing.

I have looked at the fuel in every filter I have removed & found no
evidence of water or particles.

Does anyone have any ideas why this would happen or what test I should
run?

Any help willl be greatly appreciated.

Thanks, Steven