Well if the car is coming up with an EVAP code then I would by no means rule it out as the problem, particularly if it is trying to purge too much. ABS and Trac Light will come on and stay on if one of wheel bearing sensors goes south, which one it is you will need a scan tool capable of reading ABS codes.
As for verifying operation of the Digital EGR the GP has, Im not sure how to verify operation. I can do it on the older vacuum operated ones but the digital ones Im not sure how to test them.