I have a 05 Roadster with AT as well. At about 12k miles had this very same issue and it was not good. Dealer had the car for 2+ months. Rebuilt the tranny 3 different times over that period and each time did not correct the problem. Chrysler even sent someone to dealership to work on the issue and they couldn't resolve. Finally replaced the entire transmission and converter and problem resolved. 6K miles later still no problem. According to dealer, $8,500 job. Sorry for the bad news but that was my experience. One other possible cause is low trans fluid. Understand these things are very sensetive to fluid variations. Dealer has to check, no stick.