I've posted a few times on my wonky outboard.  1988 Mercury I6, 115hp.  Seems to go through the same thing every year (I've had it for 3 years).  First outing, runs well.  Next outing, when hitting WOT, it will hesitate before planing out.  The rest of the trips, it will just plow through the water at WOT, not enough power to plane out.  If I try that 4 or 5 times, letting it rest a bit in between, it will eventually work, and will be fine the rest of the trip.  There are some slight variations but that's the normal routine.  Last time out, it planed out right away, but was clearly not up to full power.  We ran for a minute or so like that and then, pop, you could hear something catch in the motor, and off it went, working beautifully.  Like always, it worked fine the rest of the time.

Over the last two years I have replaced the spark plugs, needles, seats, floats on the carbs, the primer bulb, the trigger, and rebuilt the fuel pump.  All the cylinders are firing when checked with a timing light.  I ran it out of a portable fuel tank also.

 

Someone on a Facebook boat group recommended a new stator.  My local marinas don't seem to want to work on it. They claim it's too old to get parts, but I seem to be able to get parts just fine.  Does it sound like it could be the stator?

That's an expensive guess.  Their stator does have a high speed and low speed winding, but a trigger module breaking down can cause your problem also.  One thing I learned years ago, you might want to try a new set of plug wires, and DO NOT use regular automotive wires.  OEM wires are expensive but pretty much necessary with that ignition system, or you can just add another problem.

I have that same motor that started that same problem while my brother was using it.  He just quit running it so, since it was never trouble shot, can't help you on what was causing it.

The trigger was one of our first guess's, but I replaced it and it didn't help.

You know there are two.

if you only replaced one, try the one you swapped with the other one.

I'm looking at the engine diagram at Boats.net and I only see one.  

my 1988 I6 115 has 2.  If you are looking at a parts diagram, it only shows one, but if you look at the parts description, it shows two required.

They are both just alike and one sits above the other, don't see how you missed that.

Must be a slightly different model. Only one required on mine.  I'm sure there was only 1 there when I replaced it.

 

OK, I tried!

 

A little gee wiz info

Yours must be some strange model because they made that motor assembly for many years and all I have seen have two.  The even used That ignition system on the V-6 and it also has two.  Go to Crowley Marine Mercury parts and look it up.  Or, just look on the side of your motor.

Strange.  I'm on two Mercury I6 Facebook groups, and they always just reference "the trigger".  This is my setup.

OK, I'm the dumb**S, that's what you get when you have an OMC guy messing with a Mercury.  Their trigger module is what's called a timer base to me.

What I was referring to for the trigger module is their switching module, totally different animal.

So, I guess that proves I'm not a black motor guy.

 

I have had several OMC power packs and know of a couple of the "switching" modules on friends that have caused your problem.  Since it's intermittent, without a dino or test prop to trouble shoot it, it makes for some very expensive guessing.   Most usually just try known good parts off a good motor

 

Yes! I do have two switch boxes!