So I have the same fault code. I haven't repaired it yet though. I did pull off the electronic valve looking assembly that sits between the manifold and throttle, the one with teh poppet style valve that gets all gunked up (pictured in previous posts). I cleaned it up, but it had surprisingly little spring pressure behind it.

I did eventually find that that poppet valve is supplied via the EGR cooler, and there is a vacuum actuated flapper valve on the inlet to the EGR cooler. The flapper is actuated via a vacuum system, controlled by a vacuum solenoid.

It's hard to know if this fault code lies in the poppet valve at the throttle, with a faulty vacuum solenoid, or if it's just a vacuum leak that's preventing the flapper from metering EGR correctly.

My first step is eventually going to be getting a vacuum tester and checking the lines, as that's the cheapest fix. Both the vacuum solenoid and the poppet valve device are big dollar replacement items.