Chevrolet Blazer

Hi Foros.
I write to you why I have a problem with a Chevrolet Blazer year 97 4.3cc and automatic transmission.
It happens that the changes do not pass I can select them all; that is, direct reversal etc. But the vehicle does not run more than 40 k/hy. the revolutions exceed 3500.
The only thing I have done is to fill the box with oil thinking that I was going there. But nothing.
I hope you can help me. Until next goodbye .........

Check the change depressant hose, it may be that it is released so much on the side of the change or motor and check the overmarchasi cable