Larry: Years ago I had the same problem. It started out as a short trip to the dump station on a week day with just me and my dog and not a soul around. On the way back to the dock and just before I got to my slip way, where I normally shift into neutral and glide into my slip, I found I was stuck in forward gear. I barely had enough time to turn off and circled the Long Beach Marina turning basin while I tried to decide what to do next. I considered bumping off a end dock but all were occupied so that was out. My dog looked at me as if to say "what do we do now?". I had an up wind slip and as I circled I noticed the boat slowed down when I turned head to wind. I thought maybe I can pull this off and decided to try it. My docking set up is I have a snub line so that once into the slip I can step off and grab a cleat I installed near the end of the dock and stop the boat instantly. I powered in and jumped off, quicker than normal, snub the boat off and never hit the end of the dock.
Here's the moral of the story. The shift cable is connected to the tranny in the worse location - the bilge. The throttle cable location is not much better. The shift cable had disintergrated and the throttle cable broke off in my hand.
My advise is to inspect both cables and proceed accordingly. Replace both if one is defective.