How your IRD is connected to the TV can impact a/v sync. If you have audio through a home theater rcvr, that can introduce audio delay, and D* will probably not be able to assist you. Are you using HDMI directly into your TV? HDMI have been notoriously problematic and D* will instruct you to use component video and optical or RCA audio jacks.
For troubleshooting, connect directly to TV (no home theater rcvr) using composite video and rca audio (white/red cables). If that corrects/reduces the a/v sync problem, try replacing the composite video with component video cables. If that is still better than your original configuration, replace the audio connections and try the optical audio connection.