Just wondering if anyone has touched the fuel injectors recently? I replaced the fuel injectors on my 2009. About 2 years later, the CEL came on for a lean condition. When the engine was idling, i could hear a slight hissing sound. After much searching and troubleshooting, it turns out one of the fuel injector seals was damaged when i changed them 2 years previously. It was my own fault for damaging the fuel injector seals. This might be an unusual and rare example of a vacuum leak. But it's a good example that vacuum leaks can be found in unexpected places.

Deano