My 1997 60 hp Mercury would stall above 2800 rpm’s today. Below 2800 it would run but not quite normal. After limping back to shore and getting the boat home I pulled the plugs and found quite a bit of two stroke oil unburned. And the oil reservoir seemed much lower than usual for the amount of usage since I last filled it. My first though is a defective oil pump putting to much oil in the fuel mixture. I have never hear of this. Has any one heard of such or is it possible? Thanks for any help.