I have a 1977 chrysler 130 4 cylinder outboard. After several passes on the lake I suddenly lost power and had to cruise back to the dock at a snails pace. I recently pulled the lower unit thinking I had broken the drive shaft. Upon inspection of the lower unit everything was intact. It was tuned prior to this happening. Does anyone have some suggestions???
Spark test with a tester or try running in a tank and start pulling one plug at a time and see if any of them show no difference. My guess is you lost two cylinders or one CD Unit. If spark test works next you need to check compression. A blown head gasket will give similar results.