Buy yourself a Hanynes manual, and don't do ANYTHING until you do. It sounds like your problem is NOT the EGR, which means probably it is something that may affect the EGR like the Oxygen Sensor. A Hanynes manual will not only tell you what the error codes mean, they will also tell you how to "read them" also (you jumper out two contacts and count the flashes).
It will explain with diagrams where your EGR is also. An EGR is a simple device really, they just get stuck open and don't allow the engine to idle correctly. If you rap it with a hammer it will unstick, but again if it idles ok... IT"S NOT THE EGR.
It idles ok, runs good, gets good gas mileage, etc. Sounds to me like you don't have a problem worth spending much money or time worrying about.
You can see the Haynes manual here:
http://cgi.ebay.com/ebaymotors/ws/eB...category=34233