Know this is an pretty old thread hopefully I get an answer back.

I am experiencing the same symptoms that you are describing. I have the delay in shifting from 1st to 2nd goes to about 2500rpms then finally shifts, also same for 2nd to 3rd. When down shifting only the harsh down shift is from 2nd to 1st. This only happens when when transmission is at normal operating temperature. If the transmission is cool shifts like normal.

Just wondering if the Sonnax throttle valve kit fixed the problem is all?

Would appreciate the feedback!!

 

Sorry-I lived with the issue for a while and sold the truck, Now have a 2014 Ram 3500 DRW with an Aisin and very happy with it!