Behind and Below the Carburetor there is a Set Screw that you turn in which raises the Throttle cable Bracket. Similar to this image
http://www.danhardison.com/focus/sc/DSC03878.JPG
There is an adjustment screw that sits against the "dashpot" and you turn it right (in) to lower the idle and left (out) to raise the rpms.
PO 1507 is Idle Air Control System Underspeed
there is an idle control on these cars, could also be a problem with your intake, and idle. that's what was wrong with my 2000 focus. i lowered the idle, and changed the air filter.
You can adjust the idle.
Turn the Idle Adjusting screw.
turn the idle screw!
adjust your idle screw at your throttle body and check your cold idle stage stitch at the end of your accelerator cable at your throttle body. it may also need adjusting
The idle speed is computer controlled
You cant. The idle is controlled by the ecu.
All Ford vehicles cannot adjust idle nor timing wich is pre-set at the factory and the computer sets the idle and timing, vehicles after 1990 no longer can be adjusted.
most 2000 model year focus have a fuel delivery module recall.
Look for a vacuum blockage or a vacuum leak.