I've a 50 HP Merc 4-stroke outboard, model year 2000. Location is St.
Peterburg, FL. Recently it has been "coughing" every 20 seconds or so.
Sort of like it misses a beat regularly. Seems pretty regular and to
be the same at all speeds. Doesn't really cause a problem except that
at idle speed it often causes the engine to die which is a real PITA
when docking, although it restarts easily. I've emptied and refilled
the gas tank and changed the fuel filter ... no joy. I changed the
spark plugs last November and there's probably only about about 100
hours on the engine since then. (sailboat).

I've considered just increasing the idle RPM to get rid of the 'dieing
at idle' problem but that wouldn't really solve the 'coughing' problem.
I'll certainly appreciate any advice you engine people may have.

Chuck H.