Do you have access to someone with a Tech 2 that can command the EGR pintle on and off. Then watch the actual position of the pintle while commanding it on/off. If you have 110% verified that there are no leaks caused by cracks in the stovepipe of EGR piping, check to make sure that all gaskets at pipe connections are secure, as well as the point of entry into the intake plenum/TB.
After that is verified NOT to be the culprit, it can only be electrical and would most likely be a ground/short somewhere in the harness. You may even be tipped off to this electrical issue when trying to command the EGR on/off. Have you checked the fuses/relays for the EGR system. I guarantee that the troubleshooting list is gonna ask you to check with a test light or DMM, the EGR feeds to any fuse/relay in the fuse block!
Iím at work, so I canít pull the code and ití* troubleshooting list from SI, so I will have to do it tonight when Iím at the shop.