2013 Ford Taurus Loose rattle front end

This has been tough to diagnose. At first I thought the tie rod ends. But it isn't a constant problem. Let me know what you think. If I drive long distance at high speed ( hwy or freeway) she is fine. No rattle. Tight steering. But when I pull off the freeway for fuel for example, it's loose steering and the front axle sounds loose and clunky and rattles over small bumps in a parking lot. If I drive in town at speeds lower than 50, it doesn't do it even when I slow to 15, it is fine. It is only after driving 65Mph+ for 30 mins or more. And then rattles only at slow speeds. The rattle and loose feeling is significant and embarrassing. I have 1 week left of my 90 day lemon law warranty and I don't want the dealership to get away with this. I reported it last week. They sent it in for pwr steering recall repair but did not address my concern w the rattle. Now it still does this and they are scheduling me for next week to look at it again. Kinda pissed but not afraid of court. I've had a dealer try this before. Pushing me out till it's not their problem anymore. I won that case. I'll win again but I'm more concerned with diagnosing the problem. Any ideas?