I was just reviewing this and thought it would be worth mentioning that the EGR system shouldn't engage until the car is up to full temp so its consistent with your symptoms. ZedHead is on to something there worth checking.

That's a good point, Kurby. I think I'll buy an egr block off plate and rule that out entirely then. I haven't had a chance to look at it any this week and won't until the weekend most likely.

Just to be clear, you might need to seal the bottom tube also, to be sure. There are two passages in the manifold itself, the valve on top controls the flow between them. The plate will seal the passage but if the wall between has holes, it won't matter. You'll see how it works when you take the valve off the top. Look inside and you might see some damage. Just an improbable possibility.

You still have a mechanical linkage, it could be sticking somewhere there. Usually the problems I had with the older injection engines was that the throttle plate would not close fully due to gunk, although it looked like it closed fully, you can not see those few mm...