If your LB7 is loping/surging at idle, especially when in drive, this is one possible solution to your issue.

As stated in the video, there are several things that could be the real culprit. But after plenty of forum research and talking with my local shop, we identified the supply pressure from my lift pump being to high was my issue. By cutting the return spring down slightly, I was able to relieve a little of the supply pressure to the CP3, which was enough to allow the truck to idle smooth and perform correctly.