1993 Chrysler New Yorker Transmission not going in to gear

I have a problem with the transmission not going into gears plroperly only when it's cold. I have to pull over and shut it off to reset it, in order for it to shift right. It's not a new transmission bought it used. Is there something that I can do to remedy this? Like change out the brain box or something? I can tell when it's going to do it, it's when the shifting is going into the first gear that it goes in rough.