I am trying to fix up a Mariner 15M (like a 1983 i think)...it runs reasonably well wide open, but is difficult to get down to an idle. I just found out there;s a little water in the gas so that may be the problem. I went to check the plugs and felt like there was a lot of fouling around the gaps, and small bits of black junk in the cylinder/on the inside of the plug. Is this normal??Do i have a problem inside the powerhead? Is there something I can do to flush out the engine? Also, does anyone have any ideas on how to improve the idle...Im thinking I'll change the plugs, get some fresh gas and maybe some carb cleaner and see how that goes. Then maybe move on to rebuilding the carb if necessary. Also, when run out of the water (with hose), water pours out around where the lower unit bolts on...is this normal? I know this is a lot of questions, but thanks if anyone has any input.