Try resetting the ECU, since you didn't have the code before. Occasionally I'll get a misfire code on startup, but it's just a random misfire...ECU reset clears it.
As for your idle problem, I'd check for vacuum leaks and your IACV. The PCV has no affect on idle.
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2015 Ford Mustang GT Fastback - Ingot Silver - 6M - Performance Package - Gibson Catback, JLT CAI, FR 47lb injectors, BAMA E85 tune, Eibach Sportline, BMR wheel hop kit, UPR oil separator, Steeda shifter bushing/bracket
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