Someone just gave me a 1997 Mercury 75HP. Looks like the top cylinder has 90# compression.
90# cylinder runs intermittantly.
Cylinder wear likely from no lube. No lube likely from no fuel/oil delivery. No fuel/oil delivery likely from clogged carb.
Clogged carb likely from ethanol.
Buy a compression gauge and test all cylinders. Below 100-110# needs rebuild.