My N/A was doing the same stuff. While driving down I-70 the ABS, BAS ESP lights came on, and the spoiler was going crazy. I took it to the dealer immediately to have codes run. The wheel speed sensor was showing up as a the culprit(this explains the spoiler which is speed sensitive as well as abs and traction control which also get readings from the speed of tire rotation), but everything was pointing back to a low voltage reading. I still had the OEM battery in my 2005. They tested the battery but it came back fine, right around 13 volts. I went ahead and went down to O'Reiley's and bought a new battery. (Optima) I made the purchase because the temperatures were dipping into single digits, and I run an aftermarket speaker setup which also requires stable voltage.

Sure enough as soon as the new battery was installed, all the lights turned off and I have had not a single problems since.