The pipe on the 6 is a pain to get in/out too unless the cylinder head is off -
. Remove the egr valve and rotoroot it from the egr valve toward the intake. Make sure your speedo cable is such that it is flexible all the way to the end. On the 6 there is a 90 degree bend right before it gets into the manifold. If the speedo cable does not go around that bend it will not go all the way into the intake and not root it out like it needs. Again, the majority of the build up is at the intake manifold end of the pipe. I don't worry about vacuuming it out - just rod it out into the engine and then give it the old Italian tune-up when you finish.
Dave are you saying that you did NOT get the idle to change when you activated the egr during idle but with the egr valve off you did get the rough idle. hmmmmmmm, sounds like the pipe is clear because the rough idle with the open pipe is the same as a vacuum leak. When the egr valve was off were you able to blow through it when you put a vacuum on it to ascertain the egr valve was working properly. Let me think about this one some more as the day progresses
After thinking about it for a few minutes you may need to check the line from the exh manifold to the egr too.