2006 LS Engine light P0400

[xr8 007]

I have a 2006 LS Focus. I keep getting the engine light come on, as per the OBDII scanner spits out code P0400 (exhaust gas flow something). Did the obvious google search and seemed that most people changed the EGR valve and Intake manifold control valve purge solenoid.

The only symptoms the car demonstrates is that it runs abit rough on idle when its warmed up and sitting in traffic however I more inclined to blame the engine and trans mounts for this as the idles are ok however the car vibrates abit.

So I changed both however the engine light keeps popping back up. Any ideas on anything else I can be changing or looking at? Thanks heaps in advance.