The EGR only operates under throttle to reduce NOX by reducing combustion temperature. Spring pressure keeps the EGR closed at idle. If you want to check your EGR valve it is pretty simple with it still attached to the engine. Just remove the vacuume line and plug it. Connect a handheld vacuume pump to the EGR. Start the engine and apply vacuume to the EGR. The engine's idle will start to change to try to compensate for the vacuume leak created by the EGR valve opening. The more the EGR opens, the worse your idle will get. If your idle does not change or only changes slightly, then you have a clogged intake port or exhaust tube. When they removed lead from gasoline in the 70's, the gas lost its ability to keep combustion temperatures down and with the increase of temperature came the dreaded "run on" and also "spark knock" or detonation. With the EGR bypassed or not functioning properly, your engine is more likely to detonate under acceleration, and of course, your NOX goes up. More NOX is created when your combustion temperature rises so let your car cool off prior to taking your emmissions test, especially if your EGR is by-passed or not functioning. The catalytic converter also removes NOX and need to be hot in order to remove NOX from your exhaust gas so don't let your car cool off too much. I would think you would need a fairly large vacuume leak for your car to fail emissions considering everything else was working properly. If your car is not running hot and the EGR is functioning properly, then I think you most likely have a spent converter.
Mark