I don't know if I have posted this before, but I will tell you that I discovered that after I let it learn for a while, I turned the self learn lower RPM limit up some. I found that sitting at a stoplight, or crawling while offroad, the pull on the engine from the automatic transmission would make the ECM adjust fuel trim and IAC to keep things at the idle set point. And it would get worse with the A/C on, since there is no idle bump up for A/C. So depending on what I am doing, I will set the learn RPM to 750 to 1100 RPM. My normal idle speed is 675 to 700. (I get a panel vibration in the dash or cluster if I go lower.) The higher learn rpm helps keep the idle solid.