EGR insufficient flow. EGR valve was pretty bad looking seemed a bit sticky when opened so I replaced it along with gasket. reset the computer but check engine light came back on code p0401 again. I know you can test by pinching the yellow striped hose at the throttle body to see if the solenoid is bad. The engine will stumble a bit when you pinch it closed, or so I am told. However when I pinch the hose, nothing happens. I do notice that the car does idle kind of roughly. Anyone have any insight into this issue? Thanks in advance.