I don't know if this is the same as your problem, but, I just had a similar
problem with my 9.9 Mercury motor. I fought it for 2 seasons then let the
experts fix it.
Turned out it was a water jacket gasket allowing water into the combustion
chamber.
Repair shop charged me around $190 to fix it.
It works like a charm now!

Fredo
"dragonfly" wrote in message
u...
Hi all,

Just recently bought a little runabout with a 1999 15 Johnson. It seems
to feel like its missing at low speeds but runs fine at higher speeds.
I'm not experienced with boat engines, but I am with cars and it sounds /
feels like its trying to fire but not quiet. The plugs (x2) look ok and
not fouled.

Any suggestions on where to look first?

Thanks in advance for your help