90 legacy transmission problem?

[ec]

My 90 legacy has FWD auto transmission. Two weeks ago, after
stopping, the car started not to change to higher gear as far as
before.even gas pedal was pressed down. Yesterday, it just did not
change gear when started and the RPM did not go up either even the gas
pedal was deeply pressed. Now it just ran at 5 MPH no matter how hard
the gas pedal was stepped on.

Is this a auto transmission problem or timing problem?

Thanks