Our valued member Arthur Dalton ( affectionately refered to here as " The Old Geezer " ),has given the test procedure many times.
With the engine idling, apply vacuum to the EGR valve.
If the engine stumbles or dies, the EGR is working.
If no reaction, you could have an inoperative EGR Switchover Valve, or possibly a plugged tube.
Btw. It's not considered good manners to post the same problem twice!