The egr is defo open to atomsphere and the reason for this is very unknown, as i went down the same road as you, but i went further and wanted to know why, so i strip it and did a few test with vac gauges etc, the little breather pipe on the end of the egr is there to help with flow of gases, i dont know why only these engines use it thoug, but it must be writen into the map by the manufacturer...
Next due to the fault code, i would look at the throttle body for being clogged up, i will also tell you that the throttle body as a direct connection to the map code.