Ahhhh an insufficient flow code. Most often it's the map sensor. Reason behind it that diagnosis is that you don't have any EGR codes relating to the pintle stuck etc, which the pcm can test and sees. Most folks think this is an EGR code, but in reality it's a map code. The map sensor is reading the pressure, when the pcm commands the EGR open it expects to see a change in manifold pressure via the map sensor.

You may want to check the vacuum lines going to the map sensor.