Do not mess with that screw.
Clean your IAC and check for vaccuum leaks. I
I know you re not supposed to mess with that screw, but you are all too late, by this time all of them have been messed with, just like his has been. Ford originally adjusted that screw, I don't see why we can't adjust it properly.
To the original thread starter, once you get all the vacuum leaks fixed, get the engine running and fully warmed up, the top hose will be hot because the thermostat is open.
With it sitting there idling, unplug the idle air control valve. When you do that the engine should slow way down. You should be able to almost count the fan blades going by. It may run like that for a little bit and then stall. If it is still idling with some speed to it, turn the screw back to slow it down. Turn it down till you get the idle speed very slow. Once it's doing that, plug the idle air control valve back in.
Once you plug the idle air control valve back in, it will be idling very fast. And then it will start trying to work itself out. It will take a few drive cycles for it to work itself out and learn the new idle settings.
What are you doing when you set this screw? Ford designed it so a certain portion of idle air comes through the main butterfly in the throttle body, and the rest of the required idle air comes through the idle air control valve. This gives the computer full control of the idle over a certain rpm range.