Dmiz,
I am no expert but I can tell you what happened to my '91 Mariner 150 V6....mine did the same as you described....not sure if this is a fair comparison, but may be helpful?
The oil injection system failed before I bought the boat. Being a newb, I bought the boat after seeing the motor run in a tub of water. I know now..., Anyway, as I ran it, the motor kept bogging down and finally quit. Long story short, I had 50-70 compression in the scored cylinders and was fortunate that the motor was still a "virgin" and could be rebuilt. My tech said he sees this happen 3 to 4 times per year. He disabled my oil injection system so that now I premix (50:1) my fuel and never worry about the oil injection. He removed the oil resevoir under the deck as well, giving me lots of storage room. I have all the oil injection parts in a box should I ever sell to someone that wants the oil injection system back.
I hope yours is a simpler and less costly fix.
Good luck,
Dan