Who knows Dodge Ram auto.Transmissions?

I need some help with mine!
Its a 97 Ram 4X4 it started the other day not wanting to shift the second time so i changed the fluid and filter(filter was pretty dirty) drove it yesterday seemed to work just fine then this morning it started not shifting again but this time it doesn't want to shift the first time,if i bring the RPM's way up it will shift hard into gear!
I can't tell for sure if it's just not shifting and hanging up if it's slipping,i put some Lucas trans. treatment in it when i changed the fluid hoping maybe it would help.
Does anybody know what it could be? Do they make a rebuild kit for them?