Who knows Dodge Ram auto.Transmissions?
i had the same problem om my 2002 ram,,would shift manually,,but not auto matically,,,and not always manualy,,truck was and is stil under warranty,,they had it fixed in 2 hours,,it was a pressure valve,,i know some one else had same problem on 2001 ram,,replaced it,, never a problem again,,
hope you get it figured out with out to much trial and error,,,