I agree, it looks older. By 1988 I would have expected a fade paint job and aluminum rims. It looks more early 1980s . If you post the serrial number, I MAY be able to narrow it down. I can decode the Japoanese built frames, but do not have a really good handle on all the Taiwanese built frames. Alternately, you can check the components for date codes using the reference material at the Vintage-Trek website.

The Sport is entry level and was typically at, or very near, the bottom of the line, depending on the year.