I was saying the engine runs lean when hot (as opposed to running rich when cold), hope that makes sense.

The engine should run near stoichiometric when hot, and rich when cold. And yes, I realized what you were saying. I'm saying that engines that use speed/density systems (the great majority of, or possibly all fuel injected Honda/Acuras) to meter fuel don't experience leaning out of the air/fuel mixture due to "unmetered" air. As such, a vacuum leak shouldn't affect the air/fuel ratio, whether the engine is hot or cold.