sounds like your cluster is just taking a crap on you.
It is possible that the sensors themselves are going bad, but I doubt it.
Clusters go bad.
I had a car that the fuel gauge would act up occasionally, then the speedometer would randomly cut off, and with the speedo not working, the odometer won't work, then the coolant temp gauge would only go between the bottom line and the next one up, no higher or lower. Eventually, it all just stopped working. The tach was the last to go.
Swapped out the cluster, and everything was fine.