I have a 2004 pacifica fwd. I took it to the shop to get some suspension work done and all of a sudden, it doesn't want to reverse! It seems like it is trying to catch into gear but it won't. Driving in foreward is no problem. Shifts fine but not reverse.

 

Could be something simple like alignment of the shifter or something complicated like an internal transmission failure. There's no point in guessing. Get it in to a reputable transmission shop for some proper diagnosis.

 

Shifter cable misaligned or could be the tranny it self.

 

My 07 is doing the same thing did you ever figure out what was causing yours to do that?