I have a 2000 Mecruiser 350 MAG that's running rough. It feel's like it's running on seven cylinders and won't plain out when loaded down. The miss is from idle all the way up through the RPM range.
The problem started last winter but would go away after the boat warmed up a bit. In spring I tuned the boat up. (New cap, rotor, wires, plugs fuel water separator. At first the boat still ran like crap but then the problem had totally gone away through the better part of the summer. Now it's back
The cap and rotor look ok and so do the plugs. No water in the fuel water separator and I changed it out again.
When it first started acting up again I hit a roller and the boat started to run great again briefly. That kind of has me puzzled and so does the way it had disappeared at the begging of summer.
I also noticed the temp gauge dipping at one point and I changed the thermostat out. (it would drop from 165 down to 130) Now that I've done that it runs at 170-180. I think I might have the wrong thermostat in it but I'll get that figured out later.
It's kept at a remote lake so I'm trying to avoid hauling it out this early but it's looking like I'm going to have to see if it's throwing a code or not.
Any help is appreciated !
PS, New coil too.