I don't believe it will "kick down" from 2-1.
If the car is in drive, and you put it under a load, it will "kick down" from 3-2.
The transmission will auto shift as you decelerate into 1st gear as you approach a stop...
However! I feel that a properly adjusted kick down is crucial to a properly working transmission! Make sure your kick down is installed properly, and is functioning.
Early mustangs had a cable that attached to the lower end of the accel. pedal under the car. This cable is adjustable as the end is threaded. This may be your trouble.
Thanks for illustration. The kick down linkage is tight and accurate, and functions well between 3 and 2. Howerver, I still don't get the 2 to 1 kick down. The answers thjat I got weather the C4 can do that or not are not clear to me. Can the C4 kick down from 2 to 1 at slow speed?