I have a 1994 Evinrude Ocean Pro. I ran across a mud flat about a week ago, when this all started. The engine stop peein out the hold in the back. When i got home i cleaned it out and flushed the system. Got it to start peein out of the back and the water became clear. I changed the spark plugs. Now when i dropped my boat in the water i start the motor it runs great, but when i stick it in gear it shakes the whole boat. When i give it a little throttle it still shake but if i hammer on it it runs great, and continues to run great till i left off the throttle until i hit neatrul. Any advice on what to do here would be great.