Hi,,,and im brand new at this boat stuff. I have a Yamaha 40hp Engine on a 2020xl Pantoon! Numbers on the side of the Yamaha are 6E9 C40 PLRV Don't know if that helps. The motor idles poorly after driving on a fresh water lake for 1/2 hour or so. Almost impossible to start again. Im using 50-1 oil mixture & I turned the idle up a little higher with the screw for the idle. Seems to work a little better. Because I was all alone 12 miles from the house I also turned the 2 screws "One above the other" 1 turn counter clockwise...I think its either gas or air flow but like I said I was in a pinch. It seems to be running better. The engine is immaculate, so is the boat & running full throttle the engine runs like a top. I also changed the plugs. What I would like to know for now until I get a manual, is what are those screws that I turned? Gas? Air? And whats next if it reoccurs. Hook or by crook I want to learn all I can about my engine. I was also a service tech for 20 yrs on other mechanical things so I chance adjustments without knowledge from time to time. Thanks for allowing me to post here. Nice site to go to!!