Recently purchased used '16 Ram 1500, now got 44K miles on it. Recently had the 8 speed transmission stick in third gear, limp mode is a term I've seen. Stayed stuck through two complete stops but after third complete stop, it downshifted and then ran normally. Dealer could find no error codes or recreate the issue. Got messages on the display saying "service transmission", "service shifter". Any advice for a new member of the forum?