Wasn’t sure how to title the topic but hopefully this will work. Have a 2002 Cat 310 with the standard universal engine. Was out sailing over the weekend and had some issues when engine was above 2000 RPM’s and engaged in forward. As I crept above the 2000 mark the engine would sputter for lack of a better term and drop down below 2000 RPM. Once or twice the engine completely shut done, most times by managing the throttle I was able keep motor engaged. Issue did not occur when engine was in neutral, engine would rev up to 2800 RPM without a problem. One of my thoughts is that as we have had significant marine growth in our slip area the zebra mussels are interfering with shaft. Any thoughts regarding what could be the issue are greatly appreciated. Thanks.