I have a p0401 and this is what I've done. Replaced the DPFE,EVC, and cleaned and thoroughly inspected the EGR. When I pull a vaccuum on the EGR at idle speed the engine only moderately slows down and then levels off to a slower but somewhat steady idle. I do not have a vaccuum gauge but I did connect a hose to the line going to the EGR and drove the vehicle at different speeds. I could feel a vaccuum at certain times and not have one at other times while driving. I have cleaned the hoses to the DPFE sensor as well. While cleaning the intake into the manifold where the EGR connects I removed alot of gunk. Is it possible that further down the in the intake it is clogged up? If so, can this be removed and cleaned. I sprayed Carb cleaner down into the intake but could tell no difference before and after this cleaning at idle with EGR 100% open.

 

I foun d the problem thanks to this website. The ports going into the intake manifold where clogged.

Thanks