Any boat repair near Massena NY?

I have a 1988 Mercury I6, 115hp.  I've had it about 3 years, and it has gone through the same cycle each year.  First outing, runs great.  Next 1 or 2 outings, when I throttle up, it will hesitate a second or two, and then take off and be fine.  After that, at the beginning of each fishing trip, when I throttle up, it will dog down and stall, or just plow through the water without planing up.  If I throttle down, or even shut it off, fish a few minutes, and try again, after 4 or 5 times, it will throttle up and work fine the rest of the trip.   I've changed plugs, trigger, fuel lines, needles, seats and floats, rebuilt the fuel pump, all to no avail.  I can live with it, I only paid a few thousand for the boat and motor, but I would get it fixed if I could.  I tried a local mercury dealer and although they didn't outright tell me not to bring it, they made it clear it was too old for them to work on.  Anyone got any experience with motor repair in my area?