1982 mercury 115 carb issues?

[Bassindave]

I have an 82 mercury 115 mounted on a 16' 82 champion bass boat that ive been fixing up over the past year now and im extremely close but still not quite there. over the past year ive replaced switch boxes, lower unit, water pump impeller, rebuilt all carbs and replaced two of the floats sense the originals appeared swollen, throttle cable/s, steering cables, and im sure other things im not thinking of at the moment. Anyway, my problem is i cant seem to get it to run quite right. It starts right up when in the water now idles ok switches into gear and runs great has great whole shot and power throughtout all rpms but it seems the idle fluctuates by several hundred rpm at times. After running at or close to WOT and then coming back to neutral it idles at 1,200 then i rev it out of gear and it go's back down to 850-900 and runs fine. Sometimes when i shut it off and turn it right back on it will start and idle at 600-700 and after a quick rev out of gear idle at 850-900. Ive also noticed when running it on muffs a few moments ago that smoke comes from the bottom carb after its shut off, not to much but its there and i was wondering if that meant anything. Im at a loss here and have no idea what to do next as ive searched the forums in every way i can think of and cant find my problem so i figure its time to make my own. Any feedback here would be greatly appreciated so thanks in advance!