Cleaned the Mass Air Flow sensor following YouTube videos - no difference

Tried tapping IAC with ratchet while it was idling high - no difference

Next step - spray hoses and IAC as JBrew rec'd or just replace IAC (motor craft part in hand)

 

Also seems to happen just as much on CNG...and moreso when it's hot out (definitely on 95-100+ days out in Vegas)

 

Do you not have a OBDII scanner? That could help a bunch.

 

My money is on the IAC. My son's '01/5.4 was doing the same thing and a new IAC fixed it.