Trying to adjust my idle.

Screw A has what looks like a spring on it. I started messing with it and it doesnt seems to do anything. I also forgot to count my turns and think i might have messed its adjustment up.

Screw B I havnt touched

Screw C I turned it some and it appeared to affect my idle. i used it to set my idle down from 1000 to 800

Edit: Sorry for the large pic

 

That's why it's best to pay the fairly small fee to get a professional tune up,
if you can't identify the adjustment mechanism, you really have no business messing with it..

 

you wot mate? this is yotatech. why let someone touch our trucks when we can do it ourselves

 

Think I got it figured out. I'll leave this here in case someone comes searching.