I have a 90 ford probe v6 3.0L and I want to change the idling on it. How do I do this?

Make the adjustment at the throttle cable. The procedure is likely along the following lines. Turn the outside nut counterclockwise, until the desired idle rpm is reached. Then, holding the outside nut with an open-end wrench (likely 12mm), tighten the inside nut (likely 12mm) clockwise. This will "lock" everything in position.