Have you checked your tranny fluid recently? If it's low the tranny will tend to slip a little. Either that or else the tranny just simply needs to be replaced. Chrysler trannys aren't great.
1999 Chevrolet Camaro SS (PC'd)
1994 Chevrolet Beretta Z26 Q4 (W41 M90'd)
2004 Chevrolet Silverado 2500 (4WD)
My wife's cars:
1971 Dodge Charger SE (stock and original 383 auto)
2004 Subaru Impreza WRX (kid-hauler)