Just a possibility, I want to run by you guys.

When I start my car when it is cold (i.e., been sitting all night), it will stumble pretty badly under low RPM loads. Once it warms up (2-3 minutes or so), it goes away.

Now, I'm wondering if there is any way that the AIR pump system could be introducing unmetered air into the engine somehow, causing the stumble (which feels like it's running lean).

What kind of leaks would need to exist for this to happen?

Thanks for your thoughts.