Re: 1995 Twilight Cruiser Stalling Problem....
You may have more than one thing going on. The stalling sounds like a shift interrupter issue. If you are mechanically inclined you can adjust the shift yourself.
The poor hot restarts sound something like fuel, carburetor, or possibly timing (distributor).
Is it injected or carbed? What I am about to say is for carbureted engines.
Put the throttle control in it's start position when you go for the restart so you can rev it a bit when it starts. Maybe even give a little squirt of fuel before you crank. If the throttle is just a touch above idle that may help it start a little better when hot. Just don't over rev it when it does catch.
If the gauge shows too high a temp while idling in through your slow-go zone you ought to put the trans in neutral once in a while and bring the RPMs up, this will lower your engine temp if your engine is any thing like my 89 5.7 Mercruiser.
My shift interrupt causes my engine to stumble when I am docking sometimes, it happens when I go straight from reverse to forward. My shifter isn't perfectly adjusted and that's one of its' imperfections.
Why not get your mechanic to drive the boat like a 5 MPH zone after it is warm. He can experience the problem firsthand this way.