There is a little plastic piece that the end of the throttle cable attaches to, that breaks off and your cable is no longer pulling on the throttle plate.

I have seen that fail in some cars.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)