I finally got my boat repaired and the reason for stalling may be something you guys will encounter. It's a 1999 200 ox66 that ran perfect but would stall every couple of minutes when running at cruising speed. The culprit was the backflow valve on the fuel line. For some reason the small internal aluminum cylinder in the valve that slides to open/shut position had corrosion and was stuck. The position it stuck in allowed some fuel to flow but not enough to keep the main fuel reservoir recharged and would starve the main fuel pump after running several minutes. The fitting can be taken apart and the plunger removed if it is stuck and causing the above problem. The fitting I am referring to is item #24 on the attached diagram.