Question? 24 valve engine egr valve - Code P401

I have a Code P401 (Insufficient EGR flow) and all the system vacuums seem to check out OK.
My Question is if vacuum is applied to the EGR Valve at idle, should not the engine drop in RPM for that moment? I have always checked these valves in the past by applying suction to the valve and getting a quick check if it is working. Usually about 5-6 hg of vacuum will do.
In this vehicle I can hear the EGR valve opening but no change in engine RPM. Can this be normal in this vehicle? (97 Sable 24v code s) The only thing that I can think of is the tube from the EGR Valve to the exhaust manifold may be clogged but I question whether a tube of this size could clog up. Anyone?

If the engine is otherwise idling fine, yes, opening the EGR valve should cause the engine to nearly stall or stall. It basically provides a large vacuum leak when open at idle.

-Rod

Ok Thanks, It appears that there must by a clog somewhere in the plumbing. I guess that I will have to open it up.

FIXED - Remove the Throttle Body (4 Bolts) and between it and the upper intake manifold is a channel that connects the EGR Valve to the air intake. It was clogged. A Common problem on this engine.

Glad you got it fixed, and the Forum really appreciates you taking the time to follow-up with what you found to fix it!

-Rod