Electro valves...

[wheeler]

With engine off apply vacuum directly onto the EGR valve & it should hold vacuum. press the release valve & you should hear the valve snap shut.
Next test you can do with Mityvac connected directly to EGR valve. Have engine idling & live data readings up on diag tool. Check to see if the airflow reading drops as you open the EGR valve.
Remember when disconnecting any vacuum pipes off the components when the engine is running to temporarily plug the pipe with a small bolt or screw so you dont have a vacuum leak.

[Rhothgar]

With engine off apply vacuum directly onto the EGR valve & it should hold vacuum. press the release valve & you should hear the valve snap shut.

Obvious really. Sometimes easier to ask someone with prior knowledge than struggling to re-invent the diagnostic thought process wheel...

Next test you can do with Mityvac connected directly to EGR valve. Have engine idling & live data readings up on diag tool. Check to see if the airflow reading drops as you open the EGR valve.

Not so obvious so thanks for that.

Are those screenshots from the Mechanic's Handbook? I never think to look there.

There is a separate tool not shown there for connecting a vacuum gauge between the butterfly housing and a intercooler pipe.

[wheeler]

Only ever used a Mityvac that has the pressure gauge built in. It comes with a verity of T-pieces etc for different applications.