Ironic that you posted this yesterday. I've been working with my shop to figure out what is causing a CEL on my car. I blew the AOS a few months ago and I'm getting a Bank 1 adaptation code. My car is an 01 S with ~62K miles, daily driven.
They had the car yesterday doing some MAF logging and threw the car on the rack to check out the underside.
Basically they told me the same thing. I have cracks at the port welds on the front cylinder on each side. Evidently bank 1 is worse.
We cleared the code and I am driving it again. But I also found out I have two drips on the bellhousing... RMS starting to leak. So I was instructed to burn out the clutch, and come see them again
At that point I'll probably deal with the whole sordid mess.