I have this 6 Hp evinrude which I've been working on a while . I have cleaned and rebuilt the carb. New spark plugs and 3 new coils , I'm getting good spark and I've checked compression which is good . I can start the motor , but it will run at higher speed, but when I try to slow it down for an idle ,it will stall. I've tried to adjust with the slow speed screw, but it still dies off. I've noticed when looking down the throat of the carb on the inner side of the throttle butterfly., there seems to be a 1/16 threaded hole., which the oem manual doesn't mention. It seems to me that this should have a plug in it or something. Does anyone know anything about this?