When warm shifting transmission into reverse or low will stall the engine

Hello thanks for using 2CarPros.

it seems your idle control defected or need cleaning,at cold state engine does not stall because its idle speed will be high,when the engine warms up idle speed decrease engine starts to stall because air control valve is not working when the load increase. check fig 3 for testing the idle solenoid. as a first step check the fault codes.
check our guides:
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
https://www.2carpros.com/articles/stall-at-idle
https://www.2carpros.com/articles/engine-stalls

it also might be from transmission digital range sensor which send signal to engine control unit when load increase or decrease to activate air valve.
Please send us the fault code to narrow down our problem
thank you.

Please checked transmission digital range sensor as described above. Then get back to me.