There is one line to the EGR and two lines to the DPFE.
You might want to check out this site for P0153, P0171 and P0174. I had P0171 and P0174 once and it was a broken vacuum line. Yours could all be related to the EGR.
Maybe a gasket is leaking (?). Others will chime in with their suggestions.
http://www.v8sho.com/SHO/TSB0197HO2SServiceTips.htm
