its a 85. all i found were two screws one on the center facing the driver side and one on the front facing the passenger side.

 

Both the idle mix and idle/rpm set screws are on the driver's side. The idle/rpm set screw is the rear one, the mix screw originally had the plastic/metal limiter cap. The one you found on the passenger side near the air pump is for the TPS, leave that one alone. If you changed it, you will need to follow the trouble shooting guide in the FSM to reset it to where it should be.

One should always know what they are changing and what it does before making any changes. If you don't know, leave it alone until you learn what it's for and what it does do. Making random changes here and there without the concept of it's funtion on the system as a whole often makes things worse. Then you have to remember what you did change and return it to it's baseline settings before you can start over of fine tuning.

Skip the Haynes manual, while it does have some decent pics for reference, the factory carb manual will teach you some of the theory of how the Nikkis work. If you don't have a copy of it, download it from the link in my sig line.
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You have to get down pretty low to see the idle set screw. It's located right near where the throttle cable connects, just a little lower and forward. Once you find it, you'll be surprised you didn't see it before.