Cavalier 92 Convertible, problem with the trans

How,

I have a Convertible Chevrolet Cavalier 1992, it has a 2.2 engine; I am looking for your advice since the automatic transmission when the car turned on and putting thunder speed, had told me that a bone -shaped engine had to change, changing but the sound persists, it is only at the beginning, already on the way they enter perfectly.

Another situation is when I go on a road sometimes the transmission stays at 3rd and when I have to decrease speed for a stop, it does not return, and I have to go down manually to first, but it goes out. At first I did very little, but now it is very often (it is only on the road, in the city so far it does not).

I ask for your advice since I have had bad experiences with some transmissions workshops and I want to be better oriented.