I have a 230hp 305, with a Mercruiser Alpha 1 (1986) and this year when I
run the engine there are a strong smell of gas fumes, the engine is running
rich. It also runs a little rough. Would turning the mixture screw fix
both of these issues? I had the carb rebuilt 2 years ago, and tuned up the
engine the same time. It's not running that rough, and but rougher than
last year. How long do spark plugs and wire last? I also have electronic
ignition if that matters.

Thanks,

Glenn