1999 Chevy Cavalier cluster goes wild

You can remove the cluster and clean the connections with electronics cleaner, see if problem persists. If it does, then generally you will have to replace the entire assy.

The dealer can also remove and test the IP, but if it fails the test, they will almost always replace it, rather trying to fix it.

Try a used IP from a junk yard. It may be the least expensive solution.