That is for the cruise control, it has nothing to do with how well the truck runs.
But it may fix your cruise if it does not work.

Do like already suggested, clean everything up good, especially the idle air control valve.
Take it out, DO NOT move the plunger, clean it with carb cleaner, use a old toothbrush if you have to, then put it back and see what happens.
The IACV is what controls how much air the engine gets at idle, if it is clogged or not working the truck will not idle.

 

zing. nice one!

yea...99 problems but that aint one.