Is the delay the same on all three inputs, and was it there with the Denon? It's rather unlikely that the 990 would cause the audio to lag behind the video, as it is usually video processing that causes things to be the other way around.
What are you using as video connections? I presume component video? As an experiment, try S or composite and see if they delay is still there and still the same.
Most importantly, what is your video display?
There is no currently available consumer product with video delay. That's REALLY expensive to do, and again, it is not something that is generally needed.