p0401 again

On my 97 Windstar, with 3.8, about 85k miles,
After replacing the dpfe, my p0401 changed to p0402, so I figured I might as well replace the egr valve also, then I got the code that my intake manifold runner control was stuck open, so that got replaced.
Now the p0401 code is back, so I cleaned out the egr ports in the lower manifold (they were pretty gunked up). Reset the codes, but the 401 code comes right back. Anybody have any ideas?

I wonder how the vaccum line to the top of the EGR valve is.......
That line goes to the EGR vaccum regulator solonoid...which is mounted on the back side of the upper intake manifold.....driver's side. It has another vaccum line....which is its vaccum source......which connects to the PCV line. There is also an electrical connector on the EGR vaccum regulator solonoid.....which connects to the PCM.

I did read about the filter in vaccum soloniods getting gunked up...and causing problems with the operation. If you look at the solonoid (look at the one mounted on the firewall....on the driver side....to see what I am talking about). There is a little cap on there....that has a felt filter in it.
It should be able to "breath" a little at all times.

You can spray some SeaFoam into the vaccum part to clean it....but the only real way to clean the little filter is to remove the cap.....and filter.....clean filter....and re-install.

It is NOT easy to even see the solonoid.....

The solonoid that is mounted on the firewall, is the gas tank vapor recovery solonoid.

Thanks, I'll give that a try - it looks like it is mounted to the backside of the engine, is there a way to see if I'm getting vacuum to the egr valve? ?

The vaccum is only present during certain operating conditions.....which does not include idling in the driveway. It is OK if there is a VERY SLIGHT amount of vaccum present at idle...but not very much....if any.