Above you said the temp sensor (ECT) reported good values so why replace it?

You can check fuelling via LTFTs (see below) and other OBD values. Or get a tailpipe test (4 gas is best).

Do a sanity (plausibility) check of other engine sensors such as IAT, too. JTIS shows the ones on the STR engine best but a fair idea is here www.onboarddiagnostics.com/page02.htm

 

This TSB says that the ETM checks the gauge but the IDS is needed to completely test the cluster.

Might just take a basic diagnostic charge at the dealer to rule out the cluster?
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