93 4runner electrical problems

If there was a dead short in the circuit, the fuse would blow immediately. Since it takes 5 seconds to blow, I would suspect a hot wire making intermittent contact with ground or a high draw somewhere. I'd start with stuff that has a fairly high amperage draw to start with like the heater fan, driving lights, mooonroof, and power windows. Start with anything that is aftermarket or that has an aftermarket accessory tapped or mounted nearby.

I forgot to add this information in my original post. I have noticed some smoke coming from just behind the engine, low on the firewall. It appears when I put a 10A circuit breaker in place of the fuse. Do you know what could be in that location. Thanks for the info

the heater blower and heater resistor may be in this location. Obviously, smoke is an indication of something burning, and the blown fuses are preventing the problem from becoming worse. I recommend that you remove the circuit braker and get it fixed ASAP before you really have a problem!