Mazda offers a tip that applies to not only their vehicles but all vehicles regardless of make and model/year.

If an engine is replaced after an internal mechanical failure, clean the intake manifold internally before installing. If the intake manifold is not cleaned properly, metallic debris from the original engine may reset inside the manifold, allowing debris to be ingested into the new engine.

If the intake manifold cannot be properly cleaned, it should be replaced with a new manifold.

Metallic debris from the failed engine can easily be trapped in the original intake manifold.