My Instrument Cluster only powers intermittently, what could this be?

If any control module including an instrument cluster is working intermittently, the first step would be to check the wiring. Disconnect the harness plug and inspect the wiring for any loose, bent, or corroded pins.
 
Also, make sure to check the grounding for that harness. Usually, it's further back behind the dash mounted to the firewall with a single ground wire splitting from the main harness and is secured by a nut and washer to the chassis of the vehicle.
 
Sometimes, these grounding wires can become corroded or loose over time. If your unit is still experiencing intermittent power loss, we can do a bench test on our end to see if we can replicate that issue and proceed with repairs.