The pic you show doesn't match the 97 JGC PDC. ??Here is the dia from the FSM.
F#20 is the fuse that protects the PCM. The yellow plastic piece that is in the pic is F#17, which goes to the transmission solenoids.
The PCM provides 5v to all the sensors, transmission, TPS, MAP, 02s, Cam, Crank, Temp sensors. It usually a problem with the 02 leads, getting worn through by the drive shaft causing a short. It can also be a wire that has worn though due to a sensor that has been re routed incorrectly. Check around the exhaust and bell housing. If you keep replacing the fuse without first relieving the short, you could fry the PCM.