EGR passages clogged up, especially around the throttle body assembly. You will have to take that apart to examine it closely. Mine had the same problem and the egr passage below the throttle body that is molded within the same body, was clogged with all sorts of carbon and soot. I had to brush it out and sprayed TB cleaner. This is a maintenance item that needs to be done on our cars, generally around 50 to 60k; sometimes sooner depending on your emissions. Some folks do it sooner, especially after encountering problems with their CAT because if the right CAT clogs up, the exhaust and other goodies will find their way through the EGR passages and build up the grime sooner.
