Jgood, I have a 4.6is with 142k miles. I have the exact same issues going on - the incremental rpm steps, the throttle oscillation, an occasional slight shudder under very light acceleration. I was hoping to find something in the valvebody and have been talking with ZF North America. I ruled out fluid temp and weak engine coils. My next assignment was to monitor TC lockup percentage to see if the TC was being commanded or unlocking on its own but I need a scan tool. The more I drive it and read other forums, I'm starting to think the TC is just getting plain wore out. And when I read your post, it emphasizes that. Did you have the valvebody or solenoid rebuilt/replaced? Any metal shavings in the pan? If I can be confident that a TC replacement will fix it, I'm good with that. It sounds like it worked well for you. However, I've also heard the same issues being fixed by a simple fluid/filter change. Did you try that first?