Your OD problem is probably just the relay.

The kickdown cable is, in my experience, rarely the cause of shifting problems. My own method of adjusting that cable is to ensure that kickdown only occurs in the last tiny bit of pedal travel. You can feel the resistance in the throttle pedal when you push past the kickdown detent - you only want that to occur near wide open throttle.

You're doing more good for your transmission by driving it with fresh fluid than anything else short of a rebuild. I also highly endorse Lucas Transfix as a terrific additive for the aw70, and - again, in my experience - dropping the pan to clean and change the filter IS important. The filter screen is incredibly fine and any restriction will cause low pressure and a slow death for the tranny.