Here's an update of the problem. First, thanks for all the comments and suggestions. Like most of you guys I've been on this form several years. What a valuable resource this place is. And thanks to mainsail!
Mark ,the owner, manager, mechanic of marine pro in Cocoa Florida took a phone call and spent a good amount of time with me over the phone. I can get around 3600 RPMs when the transmission is not engaged. Just like you guys he is pretty sure that there is an exhaust outlet problem. Maybe it's over propped. If indeed the exhaust elbow is already clogged after only two light seasons of use then there is something wrong with the engine to cause it to carbon up so quickly. He speculated that it might be from a combination of: usage patterns, prop not always being as clean as it should, perhaps a little over propped, and maybe some unburned fuel from fuel injectors that are in need of servicing. Also since the exhaust outlet was raised above the water line with an extension, it is now less tolerant of a little clogging than it was before. He did not feel like the problem would get significantly worse and said he felt it was okay if I continue to use the engine. He also felt like the problem they actually get better if I run the engine relatively hard. In fact it did seem to do better after we left South Florida and came back to school. Still does not smoke but when I get up to around 2200 RPMs there is black soot in the water. Someone asked if it was the old U-shaped elbow and yes it is the old U-shaped elbow. Again thanks for all the help and advice. I'll update you after the mechanic looks at the engine.
