Your high idle is what worries me the most because you can't set the timing very accurately for "base" timing when the engine is racing above the proper level. Heck the car could even have the throttle plate partly opened to the point of exposing the vacuum ports slightly, but I'm getting ahead of myself.

Have you take a vacuum tester to apply vacuum directly to the EGR valve? Normally this only happens under load, but you can also use your hand (watch out as it can get hot in that area) to depress the EGR valve if memory serves me well enough (2-3 years ago I did this), and that will allow you to flood the motor with EGR to prove that your motor should almost stall out at idle when doing this. You can also hold the RPM higher and perform the same test at ~2500 just to see what the motor should sound like when EGR is applied. The motor will usually need to be pretty hot for the EGR to be kicking in, so don't burn yourself to do this. This can be done with the motor cold for the sake of knowing that the EGR has some dramatic effect at idle.

What sort of vacuum readings do you have too?