I had a similar problem once upon a time. Turns out Ford wasn't aligning properly. What they were doing was putting the car back to factory alignment specs, and not actually doing the alignment for the front end/tire combo I was running. I almost had a conniption fit when I found this out. Luckily I wasn't using the car as my primary during that time period, or I would have gone to blows with the "whacked" tech guy.
