I just bought this 4 hp. from the 1st. owner. Its in wonderful shape BUTTTTT, when you slow engine down in order to shift into gear it has a very rough miss, or no idle & some times quits. It seems to miss fire & or load up when trying to idle? After running at normal speeds it will idle fine for 15 to 30 seconds then starts this again. Runs well off idle. When I got it I changed lower unit lube, spark plug, gas filter. The owner before changed points last spring also. Oh yes, one more thing I did notice it seems to be puting some fuel out the exhaust when trying to idle. Starts on second pull almost every time. Where do I need to start looking, Carb, Spark ?........ Thanks Ya'll 