New tires and an alignment on the Z. And 3 nice days to drive the car.
It seems the stealership I bought the car from pulled a fast one on the back tires. They dismounted them from their original wheels, and swapped them side to side, so the worn part was on the outside instead of the inside. That explains why it was so squirrelly in the rain.
I suppose the alignment being off a little bit didn't help matters either. The car feels planted again.
