EGR – 1991 honda accord

I have a 1991 Honda Accord SE, automatic trans with a #12 code which is a generic EGR code. I have manually cleaned the EGR valve, used seafoam, vacuum and manually tested it. The valve holds a vacuum and the engine stutters slightly when egr is applied during idle. So from what I know that means the valve is good and the ports are clear.

The part that I am hesitant on is how much should the engine stutter when I apply the egr during idle? Mine is an audible difference but not close to stalling. Could the ports still be the cause? How can I test if the EGR is receiving vacuum while driving? I know the EGR is only applied when up to temp and speed. Is there a way to test at Idle? Can I apply brake and rev engine slightly while someone else checks the hose for vacuum? Any help to clear this code would be great!!!