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Engine rpm and injector pulse width fluctuate at Idle occasionally
The injector pulse width will continuously change as the air/fuel ratio switches around the ideal stoichiometric ratio but a lot of variation coupled with the rpm rising and falling (old school mechanics called this "hunting" ) would make look first for a vacuum leak.
Hunting - rising and falling idle speed is often associated with vacuum leaks.
I would look at the fuel total fuel trim short term and long term for each bank at idle and around 2000 to 2500 RPM.
If the fuel trims are addding fuel at idle and are near normal at higher RPM it points to a vacuum leak.
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