The throttle valve will stick sometimes after a rebuild because
of a small piece of something gets in there & sticks it.
The correct name for your kick down cable is Throttle Valve Cable
because it goes from the throttle linkage to the throttle valve,
& down shifting isn't it's only function.
As for an argument you can't get one from me, I can only give
you information, what you do with it is up to you.