I want to clarify that this isn't a "Mod". This is normal maintenance. In addition, it was written that most likely the pedal is bent and the cable is fine. This is a complete fallacy unless the truck has been in a bad accident or other event. Cables stretch a lot over time. This is one of the first things I check on every vehicle I buy. Every time you pull off the manifold or do any major work, these cables come off. As mentioned, adjusting tension is part of normal work/maintenance.
In addition, for everyone with an auto, you can actually tension the transmission cable for different responses. On my Taco I have this cable set through trial and error. Now...the downshifts are right on the money when I need the truck to get up and go. Even in normal traffic, I can downshift one and keep it there without really accelerating if I anticipate the need. Much like downshifting a manual. This does not hurt the transmission, it just appropriately sets the shift point. If you have it too tight, it will downshift to early. Too loose and it will hardly downshift. Drive it down the street, pull over, make your adjustment and try again. Within a few minutes you'll have it nailed.