It happened to mine as well, well it was bent before from the previously owner. Got stuck in the harbour because it wouldnt turn fully and had to be towed.
It could be the case. You could spray a starting fluid or carb cleaner around the gaskets that you reused and listen if there is an RPM change. Then you know there is a leak
but you said it shifts into gear but barely accelerates? I think the temp sensor works by grounding the spark, but I suppose this may not be the case if the temp alarm isnt going off.
It sounds like the shift cable is out of adjustment or the cable itself has some corrosion that is increasing the tension/compression on the shift interrupter assembly beyond its means therefore causing the stall.
I've had a very similar experience with my alpha 1 gen 1. When I got the boat it wouldnt shift into reverse. The shift cable definitely needed adjustment but only would do so much. My shift cable was fairly stretched. Upon that replacement I then got stuck in the Harbour (Halifax Nova Scotia) as...
The cable is spring loaded where it attaches to the engine on a interrupt switch that allows the shift mechanism to disengage. Once it "reaches" its shift location there would be less force one the cable hopefully returning the switch to center. Maintaining tension on the cable such as slow...
That sounds great. I'm sure you realize how quickly things add up in cost! Don't get ahead of yourself buying expensive stuff when ply will do. :)
have fun
You say you removed all the delaminated cloth? The secondary braces that were added across the beam makes me wonder if the strength of the fiberglass floor was shot. The fiberglass work that had been done looks like did the cheapest thing to make the floor stronger? I guess hard to say
Have a look under the powerhead where the shift linkage meets the engine. Possible sheared clevis pin. I would doubt that the shift dog was damaged for fwd and rev at the same time.
5k is plenty fast for the motor, but the fact that it "falls on its face" past that makes me think that the engine isn't getting fuel. I've had similar occurrences while accelerating and my carb needed adjustment.
Check the timing, and make sure you know your engines RPM limits so you aren't...
Has the ignition sensor been moved? or can it be adjusted? I believe slow mode grounds a spark limiting the RPM of the engine but that may have just been for older models.