Acura CL 3.0 Check Engine Light P0401 error code

Hi, I have a 97 Acura CL 3.0 and my check engine light went on few months ago with error code P0401 (EGR Insufficient flow). Did some research online and people suggested if I clean the EGR ports/passage and replace the EGR valve the problem should be fixed. I did all those but the check engine light came back on again after 100 miles. Anyone can advise what I can do next? Do I need to replace other parts as well or need to check for air leakage? Thanks in advance.

Did you remove the intake plenum to clean that port?

Thanks for the reply BullShifter. Yes, I have cleaned the intake plenum, and the light still came back on after 100 miles.

Hmmm, you did the whole update with cleaning/drilling the port, installing the sleeve and a new egr valve? I've never had one come back after doing the update until many thousand miles later when the port clogged again.