When decelerating the engine bogs down

That is unlikely. If this was going to cause an issue it would most likely be a fuel leak.

This could be a fuel pressure issue but we need to monitor it and see what we have. Do you have access to a fuel pressure gauge and are you able to do this work?

If so, here is a guide that we can run through. If we can confirm this is fuel related then we can go further. If it is not then there are other things we can do but the most likely cause of this is low fuel pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Other possible causes of this would be vacuum leaks, ignition issue, or air flow issues including sensor issues. Again, we can work through all this but we need to eliminate fuel first. Thanks

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Okay. Have you checked for codes. I suspect you have a possible solenoid issue but if that is the case we should have some codes that support that. Either way, codes or no codes, will point us in a direction. If you cannot pull codes, then most parts stores are able to do that for you fee of charge.

Okay. So if you have no codes and have a harsh shift then that means the transmission is doing what it is supposed to do but something mechanical is causing the harsh shift. Most likely it is the fluid but we could have an issue with the clutches in the transmission. Do you know if it is the same shift point each time that is harsh or is it all of them or varies?

Have you checked the fluid for level and condition?

Okay. That is good info. Yes. Let's start with fluid. However, the other possible cause would be low pressure so we may need to monitor the pressure when this happens. The fact that higher RPM's doesn't do it shows that when the pressure is higher it shifts properly.

Let me know what you find with the fluid and we can go from there. Thanks