Hi,
It sounds like possibly you may not be all that familiar with the "real" M3 as we like to call them - all US-spec cars have a sunroof, unless a PO has sealed it up. The only US-available options were CD changer and color choice - they all came identically loaded. Also, E30 M3s do not have any "check engine" lights, so I'm not sure what sort of information you are seeing on S14.net. (although there is a "check panel for lights, coolant, etc, but not "engine") Sometimes S14's info can be a bit dubious. Here is a good site for some basic info, run by the same person who runs the M3 SIG -
http://www.bimmers.com/m3/spotter/index.html
Just use the drop-down menu to the right and you can get some good basic info on the cars.
I've had mine as a daily driver for 7 years now, and at 208K miles and counting, it's still a ball to drive. It's essentially stock and NFS. Good luck in your search - if you find a potential car, make sure to have a knowledgeable M3 person check it out - they have a lot of quirks, but they don't require a witch doctor.
David in Nashville