who changed your Tranny fluid last? did they use Genuine Mopar ATF+3 brand fluid? if they didn't, that is most likely the cause of the problem. My first suggesgion would be to goto the dodge/chrysler/Jeep dealer near you, get 6 qts of ATF+3 MOPAR brand tranny fluid (it costs a little more, but is well worth it). Get 2 little bottles of Transmission anti-foam
In This Thread, some Tranny RTV, and a Tranny Filter. get them all from the dodge dealer, they have the right stuff. Drop the pan, put the new filter in, clean the pan up, close the tranny up, put the Anti-foam in, then add the 4-6 qts of ATF+3 that are needed to get it back up to level. You car will shift a million times better, and feel a little more responsive too.
Also, do what Si says and reset the computer.