1974 mercury 115 Thunderbolt II ignition poor acccel / cruis

Hello all, I am new to the boat world, but am an automotive mechanic, which probably makes me more dangerous than anythig else.., anyways here is the sccop, looking for some insight...

I have a 1974 (made in Canada) 115 HP mercury outboard with the thunderbolt ignition.

I bought it off of someone who diagnosed it as having a bad trigger in the distributor, and a lack of spark.

I confirmed that indeed it had no spark. I had another distributor given to me that was too long for my motor, but the leads were the same to the switch box, so I hoooked it up, grounded the distributor, turned the key on and spun the distributor (not installed), I got a spark, so I assumed this was the problem.

I bought a new trigger from a dealer ( $$) and installed it. I went through all of the setup procedured for timing, etc.. running it in my driveway with the ears on, and it seemed to run allright.

I took the boat out, and it runs ok up to about 1/3 throttle, then the more I give it, it just seems to run rougher and not increase in speed any. If I back it off down to 1/3 throttle, it smooths out and will run like this all day.., However, three times after it had warmed up, I stopped for a couple of minutes on the lake, and found it to accelerate just fine, ran smooth all the way to full throttle, and kept going good for about 2 minutes and then bogged down again and died. Egnie had been run about 5-10 mnutes at these occurances.

I tried bypassing the fuel pump, and using the primer ball to supply fuel while on te lake, This seeemd to make no difference. So I don't think it is pump problem. when idling the carbs adjust ok ( engine will die out as I adjust each carb individually). I don't thnk it is an inernal carb problem, or it would not be as intermittent.

when it ran good,and started to act up, it was more like someone throwing off a switch and it cut back immeidatley. I wonder about the coil, I removed a piece of a coil wire terminal that had been stuck in the coil for a long time prior to taking it out, and I am thinking maybe the coil is shorting out, or weak from runnig with this extra resistance inline with the coil wire. If I look down the end of the coil I can see a good contact surface though, now that the piece is removed.

When I remove the distributor and ground it, and spin it with the key on I don't seem to get good spark, just here and there. I would have expected it to go snap snap snap as I spin it. , but it is a good storng spak and easily jumps a good 1/2 inch.
Oddly enough, if I just drag the distributor body along the engine case to ground it, while turning the distributor, it will spark multiple times. I know this is diffrent set up than an automotive coil (switched on positive side via power supply) so I thought maybe that had something to do with it.

Anyways, I am loking for some advice.The seloc maual and the other manual I have don't say much about testing the coils for resistance. Most of what I find on line says the trigger is an issue (mine is brand new) or the switch box. Is ther any tests that can be done on the coil (resistance checks w/specs) that I can use, or checks on the switch box that will help me narrrow this down. Cap and wires are new. Plugs are new. They seem to be wet/fouling after running it with it bogging, so I really don't think it is a lack of fuel.
I did find one suggestion that said to change a coil at the first sign of any spark issues. But more people pont to the switch box....

Any insight would be apresicated. AND if anyone can confirm that I should have good spark spinning the distributor over when removed and grounded, I would appreciate that info too. Perhaps I got bad grounds.. although I have cleaned them all aready.

thanks in advance for any help