[AquaBum]

I have a 1995 baja 21 ' boat with a 5.7 mercruiser. when the boat runs good it runs great, however that doesnt happen all that often. Today after riding at high speed for a awhile and the boat is warmed up I entered 5mph zone and after a low idle for a couple of minutes an attempt to shift into neutral the boat stalled. Numerous attempts to restart would not work until after the tenth try,at which point it started but ran terrible idling high and low and attempts to shift between gears was difficult .this scenario happens allmost every time I take the boat out. Ive brought the boat to a mechanic but everytime he starts it it runs fine. I am at my wits end, any ideas. Also if I go tomorow and start it up it probably will run fine until I get to the same scenario that I discribed above. Thanks

[NHGuy]

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.