Thanks for help ahead of time. Initially the engine ran very rough and then would bog down. Boat was at home on the trailer. At the shop the throttle position indicator was replaced. Spark plugs and distributor replaced. Compression test showed 1-190, 2-210, 3-183, 4-205, 5-189, 6-200, 7-210, 8-212. At start up there is a lot of dark smoke and and the water coming out of the exhaust shows a film of dark oil on it. After the engine is warm and at idle the engine has a slight miss or roughness. How do I determine what to do next. This is the second engine in a boat I bought new