97 Expy EGR code

[mam341]

whats up everyone ? I need help figuring out why my service engine soon light keeps coming back on . Diagnosis says EGR! I have replaced egr valve , position switch , and pressure sensor. I also checked red ,green and white vacume lines for damage. Will have to throw much more $$$ at my engine ???
Recent code PO401

 

[spiveyr1]

Egr

Is that the code for insufficent EGR flow? My 97 had carbon build up on the EGR mounting flange. Cleaned it out & changed EGR at same time because I had one. Knew it was the problem the minute I saw the build up. Was the only code my 'ole 97 ever had.