Ours was hard to push, notchy and sticking when we got it a few months ago.
After looking things over we started fresh with a new lubed cable.
We yanked our cruise control due to other issues, but one less thing to bind up so check that over if necessary.
We left the stock double spring on because I read it was a safety thing. If under the hood now yes I can feel it is notchy sometimes and doesn't make for the smoothest return but it seems to work now.
We used a fishing weight over the end of the cable at the pedal to take most of the slack out.(leave some so it isn't tight)
We also yanked the carpet and reinforced with metal the area between the pedal mount and firewall to make it flush. There was some wierd side to side tweaking going on there which doesn't help with the routing.
Now we have a smooth pedal that returns and does not catch and it isn't as hard to push.
Looking at the old one it appears the routing inside and the tweaking of the pedal mount allowed the cable to angle off the end of the housing wrong and eat through it, causing bad binding when routed in the truck. The path it takes naturally binds the cable up more than it should in my opinion.
Ours has been fine for a couple months now so I have left it alone. If you can get your head underneath there and play around with it without the throttle spring on, you will see what you are dealing with.