Hi Moorevso,
Based on your description, this could be a number of things. It sounds like it could be internal to the transmission or it could just be a sensor causing the transmission to not shift which causes your speed to slow until it starts shifting again.
I provided a link to a document that goes through general auto transmission issues. Also, the attachment I provided is the general operation of your specific transmission. As you will see, this tells us the engine control module will control the transmission based on sensor inputs. If one of these sensors is faulty it will cause the transmission to malfunction and operate the way you are describing.
With this type of issue, I can confidently say there should be diagnostic trouble codes or DTC's. If you had your local mechanic look at it, did they provide you any detail about any DTC's that they found? Worst case, you can go to one of the local parts stores as most offer a free service of pulling these codes which will help us determine what is happening to cause this issue.
https://www.2carpros.com/articles/automatic-transmission-problems
Please let us know if you have any of these DTCs because they will aid immensely in determining this issue. Thanks
Kenny.
Apr 9, 2019 at 12:53 PM
