Transmission not shifting properly and Overdrive off light is flashing?

We need to run the codes because it sounds like you may have a clogged catalytic converter. you can get a code scanner from Amazon for about $20.00.

Here is a guide/video to show you how:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is a scanner link:

https://amzn.to/3Qi1SS6

If no codes are present, I would try replacing the turbine shaft speed sensor. here is how the job is done in the images below.