I believe that the idle is computer controlled and that you can not adjust it.
SO you may want to start with the basics... when was the last time your bronco had a tune up?
Pull your distributer cap, make sure the inside is clean of dirt, moisture, or oil/grime. Make sure the contacts are not pitted, if they are replace it, and the rotor.
Check your air filter.
Check your plugs.
If you just got the truck, change the fuel filter, this way you will know when it was last done.
I might get some dissagreement here... but it may be a good idea to throw in a can of some kind of fuel treatment to clean your injectors.
If this doesn't take care of your problem, check your plug wires.
Vacuum leaks could cause stalling as you mention.
IF none of this works out, then you will have to learn how to check for codes.
Good luck
joe