Dave - it's good to see you asking this time instead of providing some of the excellent help you have provided in the past on various subjects
. You may have already tried what I am going to suggest so disregard if you have.
Have you tried the test where you have the car hot/idling and put the Mighty Vac on the vacuum line to the egr and put some vacuum on the egr to make it open? If it almost stalls then the egr is working the way it is supposed to. The next step is to start troubleshooting the actual vacuum "signal" to the egr. I am not familiar enough with your application to help here but I'm sure someone will come along that can offer some advice.
I am not familiar with the emissions testing but are the test performed at idle. The egr valve is supposed to be closed (not recirculating) at idle.