Egr vacuum at idle

Hello! I've been searching the Internet, and this forum, and can't find an answer...

My truck is idling poor (missing). When I remove the vacuum line to the egr, it smooths out.

I have vacuum at this line at idle... Which is my problem.

Following the line, it goes back to the "duty solenoid valve"...

Why do I have vacuum at idle? What can I do to try and fix this issue?

Is my only option to replace the duty solenoid valve?

Thanks for your help.

Here's a diagram...

Bump*

My guess would be that you have the two vacuum lines(blue and green in the diagram) going to the vacuum solenoid(near the thermostat housing) flipped.
Some of these valves are designed to only have constant vacuum on one port... almost like a check valve.