'77 lebaron trans problems

i have a 1977 lebaron with a 2-bbl leanburn 318 with a 3 speed auto trans (not sure what kind of trans)

anyway, i have two problems with it:

1) it will not downshift/kickdown when you depress the gas pedal all the way down

and

2) under minor acceleration it will shift from 1st to 2nd, then back to 1st and back up to 2nd really fast. the 2nd to 3rd shift seems totally normal. under hard acceleration, the 1st to 2nd shift is normal.

i replaced the neutral safety switch for the hell of it and it didnt do anything, not that i was expecting it to...

any ideas on what it might be? anything i can try before taking it to a transmission shop and paying an arm and a leg?

any help is great help

thanks

-glen