2004 Grand Prix - ABS/Traction Control Problem won't stop

How old are your tires? And are there any differences side to side?

It is possible to end up with tires of different diameter - even if they’re the same size tire - that trigger ABS activity.

I don’t think this is very common, but I have experienced it myself (and on a GM vehicle). In my case it was all very low speed ABS activation.