If you had bought later than ’98, even like ’01-’02, I would suggest selling. But you bought before the insanity hit, in fact pretty near the bottom, so you’re probably sitting on a great thing. If you are planning on returning to SoCal, keep it! In the next 3 years it’s value may go down, or it may go up. Most of us here think down, but no one really knows for sure. One thing that is pretty certain though is that it will behave just like most other properties in SoCal. So even if it does go down, so will everything else in the area.
If your plans were to live in another part of the country, sell it!
I wonder if you might not be able to lower your monthly obligations, thus improving your cash flow, by refinancing with a 15 year mortgage. It will probably depend on your current interest rate, and the costs associated with a new loan. What do others think of that idea?