Has the water-stream from your telltale on your outboard slowed, or stopped completely? Before you bring it in for service, make sure that the water inlet on the lower end isn’t plugged with seaweed, and that the outlet for the telltale stream isn’t blocked.
If you run Mercury Quickare every fill up, you will run into less problems down the road. It is designed to keep your fuel stable, it tames ethanol, and keeps the passages and jets in your carburetor clean. In EFI engines, it helps lubricate the high pressure fuel pump and helps keep your injectors clean.