Why does my 96 f-150 shift roughly?

I just bought an old 96 f-150 4x4 w/ an automatic (with a cooler) cheap. It has the 302 V8 and 202k. The engine purrs like a kitten. Well, anyway, when I accelerate firmly and smoothly it shifts normally with a definite shift into overdrive. If I take my time getting up to speed it shifts quite roughly at 30 and 40-45mph. And trying to maintain those speeds usually results in rough shifting in and out of gear. I had the flushed just recently with no noticeable change. Is this normal wear?