My Charger idles in neutral about 13.5 to 14.0 when warm but fattens up in gear. My sensor is in the RH header collector. The gauge that I have has a narrow range, something like 10.0 to 18.0. It has idled off the charts lean, meaning something above the 18.0 limits and it was choppy and erratic.
I've had mine set to run in what was considered to be optimal, 14.7. It didn't run as strong though. I do wonder if the "Up to 10% Ethanol" in our gas here skews the numbers at all. I run richer than the suggested normal numbers for power. I guess if I were to tune for economy, I have the wrong car anyway!