I been watching your post. Have you or anyone else changed the filter in the trans recently. There is a small gasket between the filter and the valve body, that sometimes slip to the side when you put on a new filter. If it does this it will block off part of the oil going though the tranny. I'd pull the pan and check and see if its something this simple. This is a 350 tranny problem, you never see it a 400 tranny.
