I have a 2000 boxster s and had the same ingition switch problems that a lot of other people had.  I followed the instructions that were on here and changed the ignition switch.  I can get my car to start but it will only idle at 1000 rpms and if I floor it the most it would get to is 1500 rpms.  I had no issues besides the ignition switch when I made the change.  I have checked every fuse, all fine.  I have removed the ignition switch multiple times and tried again, but nothing.  I even put back in the old switch and it does the same thing.  I feel like I must have hit a wire somewhere that relates to this, but I don't know what one.  Can anyone help.
Thanks
Tim