Darin - He's got an auto.

Drop the pan, change the filter, and FLUSH the old fluid. If it still slips start looking for another tranny to drop in there. Could be your torque converter but if you're going to rip out the tranny and install a new T-converter, you're probably looking at about as much $ for a good used tranny. Go all the way and get you're confidence back.

$.02

Tom