It's hard to tell from your question. 1990 would have been under Gulf war rules, and if you were discharged because of a service-connected disability, you'd be eligible.
The VA says you must serve six years in the Guard / Reserves to get a VA loan "if you are not otherwise eligible." The easiest way to find out (and get your Certificate of Eligibility) is to have your lender look you up on the VA's webLGY system. It only takes a few minutes.