EGR valve should not open during idling. I used to test it before I took my car for CAL. smog check by applying vacuum to the valve (to make it open) during idling. If the engine dies, the valve is good. I have not done that anymore since my friend got his smog check license many years ago.
WARNING: Spraying crab cleaner near the high temperature areas may catch fire. Propane gas is safer.
Feeding the propane gas via a small rubber tube to find vacuum leak. It sounds like you have a vaccuum leak near the EGR valve.
[This message has been edited by be459 (edited 05-17-2000).]