I can run all the college national champions since the year I was born ('80) off my head, and I assure you that Auburn was not one of them.
Auburn was declared champion by the National Championship Foundation despite being on probation in 1993.
They were also declared champion by some organizations in 1983, although Miami and Nebraska were also declared as champions by other organizations.
Source = http://www.ncaa.org/champadmin/ia_football...ast_champs.html
...I didn't know so many possible "championships" existed...
BUT, sticking with the letter of the law, the true pre-BCS championships were the AP's champion and the coaches' champion, and those were the ones I remember... granted, I didn't always agree with them
...plus I still think D1 football has a fair ways to go before they get to anything resembling a "true" champion (the lower divisions don't have this problem, wonder why, hmmm)