Apologies if this has already been mentioned - I'm still new around here and getting the hang of stuff.
I took a look at the one lead that LE was willing to disclose and took a look at the potential flights. I found some old flight schedules on DepartedFlights, and according to what I was able to find, there were no flights to ABQ from Burbank at the time this lady would have been leaving CA. I took a look at routes to ABQ from LAX, and between 1989 and October of 1991, only Southwest Airlines was running a direct flight from LAX to ABQ. I know I'm assuming she took a direct route, but I also think that's a reasonable assumption.
DepartedFlights has scans of historic flight itineraries, but they're not very user friendly (i.e: they're scans and you can't use the search function on them) and I haven't had the time to sit down and really dig into them, but they do list what days which flights go out of which airports. It's a long shot, but if the airports AND the airline can be narrowed down, there might be a chance of getting more information: passenger lists, long-time staff who may remember someone, etc.