It is a 1999 Mercury 15 hp 2 stroke electric start with remots controls that sat in a barn for ten years with old gas in it. It has almost no hours on it. I had a professional rebuild the carb. It starts and idles great. It will run like a bat at high speed. But at low speed, just a little above idle it will cough once in a while. One cylinder simply miss fires and will belch out a bit of smoke. Not sure which one yet. If you do not move the throttle it will become much worse. I am used to older motors but this does not seem to take the throttle evenly. When it is not fully warmed up a push of the choke will smooth it out. What do you suggest?
