Won't go forward

[Cornbread9]

I was fishing on Lake Anna in Virginia and the boat was running the best it had run since I owned it. I had recently switched to Yamalube two trips ago and the motor was loving it. It levels out at 3800 rpms and then I hold it around 4000. I am not hard on it. I was cruising around at that speed and I don't know if I hit a small wake or a stick or just heard something hit or a part break, but there was a noise and a small wake and then the boat dropped to 2000 rpms and limped like it was in a safety mode never to go over 2000 rpms. It shortly no longer would go forward. When I put it in forward it just stalled out or cut off. I was going to limp back 3 miles on a trolling motor, but then realized it would go in reverse. It ran pretty smooth all the way back at 1500 rpms in reverse. Any Ideas?

​It is a 1988 Yamaha Pro50G.

​Thanks for you help,
Steve

 

[99yam40]

sounds like it is time to take the lower unit apart and see what you find