Transmission hard shifting in fourth gear?

You may have an accumulator spring that is broken inside the transmission. Is your ABS light on or the check engine light? If so, we need to run the codes to see what comes up, this requires a CAN scan which is easy to do. You can get a CAN scanner (Controller Area Network) from Amazon from about $32.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Amazon CAN scanner link:

https://amzn.to/3sX8MCX

Also have you serviced the transmission recently? If not, I would install a new filter and fresh fluid. This guide can help with instructions in the images below for your truck:

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Check out the images (below). Please let us know what you find. We are interested to see what it is.