Re: 1974 9.9 idle speed adjustment
Try this, turn the rich/lean needle valve clockwise until it gently seats and then back it out 1 1/4 turns (counterclockwise). Re-adjust as needed while motor is idling. By leaning out the mixture (clockwise) the idle will increase slightly just before it starts to sneeze. That's where you should leave it. I'd bet you can find the idle knob, and linkage for it, on ebay.
