If I wiggle the fuse 23 it puts the engine in reduce power mode why?

I would pull the connector on the glow plug relay and see if you still blow that fuse. If not, then the short circuit is between the relay and the engine. If it does still blow the fuse the issue is between the fuse box and the relay. A multi meter will help you find the short to ground and the relay test will reduce the places to check.

Reduced power (AKA "Limp" mode) is activated when a serious problem exists in the engine or the transmission, you need the system scanned to see what is causing the system to put your car in Limp Home Mode.

the ECM records problems with the engine and transmission and if those problems go outside set parameters then the ECM puts the car into reduced performance mode (limp mode)
Yes --if the transmission is over heating then the limp mode cuts in to protect the transmission from damage.

the "brain" of the car has detected a problem and is reducing the power available (limp home mode), get it to a garage and have them scan the odb2 data (or get a odb2 scanner and do it yourself. it will provide a fault code) the fault code will tell why it went to reduced power mode (limp home)
Isuzu OBD II Trouble Codes

run fault codes to find the sensor that put the care in reduced power mode.. Check oil and coolant levels.

Find out what the #23 fuse is for. Then check out this device or function, it may have a problem that is causing the fuse to blow.

It could be a short in the wiring-a bare wire touching metal, but sometimes an injector will go bad and short out blowing the fuse. Try unplugging all the injectors, then put new fuse in and turn key on. If fuse blows again, it must be a bad wire in the injector circuit. Each injector has a power wire and a ground wire, the power wire probably derives from the engine computer, and the ground wire definitely goes to the computer.
If the fuse didn't blow right away, try connecting one injector at a time (key on). If connecting one injector causes the fuse to blow-that is a shorted injector. It will have to be replaced.
If connecting all injectors did not blow the fuse, try the wiggle test on the wires, with key on. You may cause the fuse to blow by wiggling or moving a section of wire, and that is the likely source of the short. Separate the wires and examine them closely. Look for exposed wire, melted insulation, things like that. Look for where the wiring harnesses may chaff or rub against something, may be stretched or stressed. If you still can't find it, you may need to run continuity or resistance tests on each individual injector wire. For that you would need a multimeter, a good digital volt ohm meter (DVOM) at a reasonable price is a necessity for automotive work.

From your description it seems the dynamo has shorted. Get that checked first.

Reduced power mode is when the electronic ignition is strategically is not firing all the cylinders to prevent catastrophic failure of your engine. The reason for the GM Engineers put the reduced power mode in the vehicle is so you can drive the vehicle under 50Mph for about 50 miles to a mechanic before the vehicle completely dies.

There is an issues that prompt the ECM to put the "reduced engine power" mode to activate. Your going to have to get the DTC code to addressed the issue so the ECM will deactivate the "reduced engine power" mode.
Thank you for using Fixya and Auto Zone can scan free of charge and give you the recommendation to address the issue and as why your engine is in the reduced power mode. Good luck