Yours is not an uncommon problem..
What is happening is small pieces of carbon are breaking off from inside the EGR passage an are getting lodged in the pintle of the EGR valve.
There was a company that made a screened gasket that would prevent the pieces from entering the valve...
www.tomco.com I believe they may have gone out of business.
To remove the valve, you don't need to do more than, remove the rubber air duct to the plenum, unplug the connector and remove the 2 10mm bolts that hold the valve on.
You can twist the valve so it will come out.