This sounds like an issue with either the pressure in the unit or the fluid is low.
I would suggest starting with checking with codes and that will help determine if there is a different issue.
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
Let's then check the fluid and make sure it is clean and the proper level. If it is questionable then lets change it.
Below is the process that will help with this.
Also, you mentioned the idle dropped. Does it still do this or was that just an issue that you have had for a while and the transmission not moving is new?
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Tuesday, April 13th, 2021 AT 6:50 PM