What is the little screw to the left of the throttle body right on the throttle cable

 

Factory idle placement. It is not to be messed with. The IAC will adjust the idle for you. If you do move it the IAC will adjust it back to where it was.

 

if my IAC was not workin and i turned it would it help with a low idle

 

If your IAC is not working, try removing it and cleaning it. You can use like electrical cleaner and a toothbrush. The unit itself is a little fragile.
Make sure to clean the throttle body passage way for it too.

If it still doesn't work after that (make sure you plug it back in, been there, did that, haha!) you will need to replace the IAC.