[JustSayGo]

The EGR valve should be closed at idle. You have already proved that you EGR valve opens and doesn't leak. There is a hose from the throttle body that should not have vacuum at idle. As the throttle body opens this ported vacuum begins to pull vacuum. Make sure there is no vacuum at idle. This ported vacuum is used as a signal to open the EGR solenoid. The EGR solenoid then connects manifold vacuum (which is much stronger than ported vacuum) to the EGR valve. The EGR solenoid has a wire connected to it. When there is power to the wire the solenoid opens and allows manifold vacuum to open the EGR valve. At idle there should not be any vacuum drawn through the solenoid. The solenoid may not be blocking the vacuum at idle because it leaks, or because there is a ported vacuum signal or electrical power to the solenoid. Which hose was disconnected? The hose connected to the EGR valve or the hose connected to the throttle body?