Low idle engine stalling out

"I have a 4.3L mercruiser, las

"I have a 4.3L mercruiser, last Sat it stalled on me for the first time ever. Since then I can not keep it running, it has a low idle and I can def smell it is running rich. Previous to Saturday we had severe storms, I keep it in the water, the bilge did not automatically pump the water, when I went to the boat the next day after the storm, the water in the bilge was over the oil pan,actually covering about a third of the engine. I doubt if it is a serious problem, but I dont know much about engines and I really dont have the money to hire someone. My brother in law suggested dry gas in the tank, and cleaning the carburator, I noticed that when I moved the butterfly flap by hand it definitely increased the performance.*I was slipped when I did this* I still took the boat out and it ran fine, but when I was going back to my slip it was hesitating when I was going through the no wake zone. It stalled a few times when putting it back. Does anyone have any suggestions on what may be the problem."

"Do you think some of the wate

"Do you think some of the water got into the engine somehow ? If the oil pan is overfull (ie, some water got in) then the crank will slap the oil, and often make an engine stall out at idle."