Pull the code, you can use one single wire and put the 2 ends into the 'Diagnostic' box in your engine bay, and it'll flash whatever code it is pulling. Also, if neither you or a mechanic can find any problems with your engine, it may be a faulty check engine light, replace it, and you should be fine.
Mine has the same problem, mine always randomly turns on for awhile, and will turn off, or even in the same day or 2-3 days will turn on, then back off.. Been like that since I bought it, but I would check all your wires, check for vacuum leaks, oil leaks, anything, and have someone with a code-pull for it, or use a single wire to do it yourself, and see what number code it flashes. Other than that if there's no engine problems, replace the wire & all for the check engine and see if it still goes on/off after that.
My runner is a '92 3.slo as well.
