Your symptoms do sound like a bad EGR valve, any valve I have tested always held the diaphram when you applied vacuum. I thought I found an inexpensive one on Ebay for you ($15.87) but it was for a 4 cylinder engine. The V6 is pricey.
They are so strict in CA it's unreal. In MA we don't need a smog test after a car is 15 years old.
I don't think there is any age relief in CA. My argument is that keeping an old car running longer is one less car in a landfill but that's a topic for another thread.