Confused auto transmission

[Tanzania4x4]

I have a 94 Prado with an automatic trans. Completely out of the blue it has not been responding to what the selector indicates. When it is in reverse it does nothing. When it is in neutral it goes forward. When it is in park it wants to go forward but can't. Sometimes it works correctly but mostly it is confused. I live in East Africa and not too many understand an auto trans. I changed trans fluid once but still nothing. Please advise me. The vehicle has 118,000 ks.

[fourwd1]

Most auto trannys these days are electronically controlled. They have a mode switch mounted on the shifter (usually where the shifter bolts to the tranny). These can get corroded and report bad info the the tranny ECM, causing all kinds of problems. Something to look at.