could just need fresh fluid. i have to do that to my beater mazda, about every 30K miles. automatic.
don't EVER flush a transmission.
just drain the pan, and refill with the right fluid recommended for your chrysler transmission.
old fluid in my mazda, and it gets sluggish on shifts, and can slip a little bit.
my car also doesn't shift right until it warms up 20%+. sometimes, if i leave cold, it will get stuck in 4th gear at the first stop sign.
it's a weird computer problem...so i turn it off, turn it right back on, problem disappears. shifts fine afterwards. this does not happen if i let the car warm up at all.
if anyone f***s up your transmission, they will say it's "from age". it usually is not. it's from mistakes made in service.
i've got an AAMCO story that will spin your head. a $1200 "inspection" quote given to wife...and it was only a loose bolt.