1988 Century stalling problem

I have an Buick Century, 1988, 102,000, V6 (not sure exactly which L type though). It stalls intermittently at a stop, in idle, or even sometimes when driving, and the check engine light is perpetually on. Just had it serviced, they cleaned the MAF, and replaced the computer module, and it ran nicely for about a half hour. When started up later, it returned to the exact behavior; when first started up, it stalls, and takes several tries sometimes, then runs rough in idle, and dies again. If this helps at all, one of the fuses (the one that runs the dome light, radio, horn, and power lock) has a short, and since these are non-essentials, I haven't had a fuse in place for several months. So I wonder if there are additional shorts causing problems to the computer module? How difficult are shorts to fix?