If you entered the country legally, overstayed the visa, and Married a US citizen it is possible to apply for permanent residecy through your marriage. However, this is a process that requires some specific steps.
Here is a link to some information about how that process works.
http://www.uscis.gov/portal/site/usc...00082ca60aRCRD
Part of that process will be that you will have to show evidence that you entered legally. The I-94 issued upon entry is the usual method of this. If you do not have this document, you can file form I202 to get a replacement. Read through the link below on the form and in the instructions to make sure you know exactly what you need to do.
http://www.uscis.gov/portal/site/usc...0045f3d6a1RCRD
I am not sure about their record keeping, but it does seem like a risk that they would not possibly have that exact document from 18 years ago. However, part of the evidence you will need to supply is a copy of the passport that shows the entry stamp, so that may help the situation.
I am not familiar with FOYA ?....would you possible mean FOIA...Freedom of informaiton act?? if that is the case, i am not sure how that will help.

