2002 50HP vibration/cuts out

[brianatsunsets]

Have a 2002 50 HP on a Pontoon boat. Worked fine all spring. After working perfect on Friday went to take out Saturday morning. Rough idle. Tried to take for a ride. Put in gear and noticed a slight vibration much like weeds on the prop. No weeds and prop looks good. Tried to add speed to see if the engine would clear out. Died quickly like the key was turned off. Re-started same thing several times.
Almost seems if it is some sort of "limp mode".
Ideas????

[boats.net]

Check gearcase oil for water or metal in oil. Check compression on engine.