Had the Freestar for about 2000 miles and trac off light is still erratic. Have a new variation and combination almost every day. The latest is the Low Tire Pressure light. I have checked the tire pressure three times with three different gauges. Pressure is right on the money. (34 lbs each).
The surprising thing is that with only the Trac off light on the cruise control is inoperative, but since the low tire light has come on the cruise control works.
I want to put it on the rack and pull all of the wheels and inspect each of the sensors but just haven't found the time. I see nothing dangerous about either situation as I have driven most of my life without traction control or low tire sensors. I want to see if I can diagnose and fix the problem myself before I spend hundreds of $ on it.
I love the vehicle and it is a pleasure to drive so I am not unduly upset with the situation, just frustrated. I will report progress if any.

SIMPLE FIX:
Solution is to replace the Brake Pressure Switch located on the end of the master cylinder. Unplug the electrical connection, unscrew the switch, replace it with a new switch available from Ford for around $25. You will lose only a few drops of brake fluid in the process. Might take ten minutes including opening and closing the hood.