Need advise

[steplift20]

Ok today I started my 1988 150 mercury out board and she started right up was idling to high so I turned the idle screw to lower it, she ran great but then the idle lowered by itself and the exhaust started to smoke like as if I was spraying oil in the carbs to winterized it, which I wasn't Almost stalled out but she didn't, the idle started to get higher and the smoke was back to normal, what would cause her to do that? Should I be concerned and also this is the first year that I did not winterized her Thanks as sone as I can figure out how to put pics on here I will Thanks again