FIA-F1

I recently replaced my Mass Airflow Sensor on my 05 Boxster base and found this 4" o-ring sitting on the garage floor underneath the car. Obviously, I must have knocked it off in the operation and didn't know it until everything was back together. I now have a RPM fluctuation between 500-800 at idle. Strangely, it seems to fluctuate when I have the clutch depressed and smooths out when I let the clutch go. Regardless, my question is does anyone know if the missing o-ring can cause this RPM fluctuation? Seems like since it s on the air filter side of the air intake, it would not make that much difference. It was no fun putting the MAS in, just checking to see how critical it is to re-do.