Bad trany cooler in radiator. To test, lay radiator on its front, fill with as much water as possible. Take low pressure compressed air and feed into one trany cooler line opening and place finger over other opening. If you see bubbles it is a sure fire cooler leak.

My trany, cooler went out over 50k miles ago, and have had no problems since I purged the trany. Purge your trany until it runs bright red. I did this by disconnecting the cooler return line and starting the car and pumping out a quart or two, stopping engine, filling and repeating until bright red. May want to change fluid again in a few thousand miles or sooner if color is not correct.

The AW series of tranies are tough and should cause no probs if you change the oil.

Good luck,

dick