Hang in there a second.
Dan.. are you saying that a cracked EGR tube may cause this code? Wouldn't that be a too much flow or lean code instead of a insufficient?
The name of the code not being listed in the thread is a detriment to the thread.
EGR SYSTEM INSUFFICIENT FLOW
Here'* the GM FSM info on the code.
I've seen many guys spin their wheels checking the EGR etc because EGR is named in the code. The problem is usually not an EGR though. The system reads the flow at the MAP sensor. If the MAP doesn't see a change in flow as it'* expecting when actuating the EGR, it sets the code. Please check your map sensors and the vacuum lines going to it if you are supercharged.