Generally, problems with these symptoms are going to be an intake problem of some kind. Some general pointers:
Check that your filters are ok, and all through the intake tract that nothing's loose or leaking (joints/fittings in the intake tract, PCV hose connections, EGR vacuum connections, MAF sensors, etc).
Ditto for the exhaust: if some of your exhaust bolts have rattled loose or a gasket has burned out and caused an exhaust leak, it can cause minor tuning problems as well.
Clean the MAF sensors. It's a very easy job. Buy a spray can of MAF cleaner at the auto parts store. They come out with two tiny bolts each, just spray them down from all angles and let them air dry a few minutes. Do not touch the part of the MAF sensor that's normally inside the intake with your fingers, or to anything else. Just hold it by the wiring harness connector. Do not over-torque the bolts when re-installing, they're tiny weak bolts and you can snap them.
If the ECU has likely been reset recently (battery disconnect, fresh tune uploaded, etc), you may need some drive time for things to settle down.
If the ECU has been reset, and/or you've made any changes to the configuration of the intake tract, it wouldn't hurt to re-do the Idle Air Volume learning procedure. You can do this at home by some careful timing of the ignitions switch and the gas pedal, it's detailed in the Service Manual on pages EC-18 through EC-20 (you may need to do the 2 referenced simpler procedures first to re-learn the throttle close position and the gas pedal zero position).
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