why my 2007 Subaru Outback has high pm while driving when I shift to Neutral. ?

Is the check engine light lit?

If the idle is high I would suspect a vacuum leak or a dirty/faulty IAC (Idle Air Control).

Spray-clean the throttle body thoroughly; gummed up one won't throw a CEL.

Thanks for all answers so far. No- I don't have check I gone lights at all. I reaped a bad air filter today, but remain the same.

Sorry, the car has no check engine lights

I drove after checking vacuum hoses and stuff but the car still with high RPM while driving and shift to neutral, probably the idle control valve Ned's adjustment or replace? Any idea? Appreciate all answers.

OK, maybe it won't trigger a check engine light, but, that doesn't mean you don't have one.