Hello, I have a 89 or 90 20 hp merc that was stored with fuel in it for aprox 8yrs when I pulled it out I cleaned the plugs and fuel filter and added new fuel. Started on 3rd pull it seemed to run well. When I took it out this past weekend I noticed it had a moderate miss and stumble during the 1st quarter of the throttle but ran well from there to wot. On the 2nd day the stumble/miss got worse and started to stall at idle through the 1st quarter of the throttle but again good from there to wot. Seems like the idle circuit Is plugged up runs seemingly rich during low idle operation but good above that. Any suggestions ?