The EGR Vacuum Regulator (EVR) controls the opening and closing of the EGR valve. The EVR is an electromagnetic solenoid and should have between 20-70 ohms resistance between the pins. +12volts should be constant on one side from the EEC Relay, the computer controls the ground signal when EGR flow is needed.
When the EGR Vacuum Regulator (EVR) is off, both ports vent slowly to atsmophere.
To test it mechanically check to see if vacuum is present at the EGR valve with the electrical connector unplugged from the EVR. The top port should not have vacuum! Because that would open the EGR at the wrong times.
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.

Possible causes:
•Damaged EVR regulator.
•Corroded or dirty connector
•Damaged EGR valve.
•Faulty Vacuum system.
•Broken wire in harness.
•Grounded harness.
•Damaged Computer.