Have you tried to take the egr off and clean it. Sometimes you can clean them and get them to seal a little better and last another few thousand miles.
Usally if its just the sensor of valve it will still run ok sometimes or until it gets hot. Leaking egr will run like crap all the time. You can pull the codes and see of the egr sensors are not responding.
Replacing the egr is not that expensive. Try rockauto.com if all else fails they usally sell a cheap one.
Has the mpg gone way down usally a sure sign the egr is bad. Even unhooked it may still be causing bad milage.