I own a 2009 corolla. On 7 occasions it has revved uncontrollably. It is a random and dangerous event. It only has happened in park, reverse, or when slowing to a stop. It has only happened in the winter months (4 times last winter and 3 times this winter here in PA) I can’t duplicate the problem and my toyota dealer has been no help. In a few short seconds the tac goes from 2000 all the way to 6000 before I shut the engine off. I never have let it keep going.
It is not caused by the carpet.
You may want to look at this. http://abcnews.go.com/Blotter/RunawayToyotas/toyota-recall-fails-address-sudden-acceleration-cases-expert/story?id=9173621
Tester
Document, Document, Document. This car is under warranty, and by making sure the dealer is aware of the problem can there be any real solution.
Maybe the floor mat recall is causing the problem. Your car doesn’t seem to be a part of the recall, but it still could be a problem. See Toyota’s official statement here: http://pressroom.toyota.com/pr/tms/toyota/toyota-consumer-safety-advisory-102572.aspx?srchid=K610_p229454330
And, some angry owner’s statements who are not believing this is the cause here: http://abcnews.go.com/Blotter/RunawayToyotas/sudden-acceleration-toyota-cars-owners-rebel-accidents/story?id=8980479
Hmm - I was just about to suggest the carpet and got your your last statement. The floor mats do get stiffer in winter, and it did just bite me in my truck last weekend 
LEMON LAW time!
If more people would simply use the legal resources that exist, rather than tolerating problems, then perhaps manufacturers would come up with “fixes” more rapidly.
To see the details for your state, go to www.lemonlawamerica.com/
I can tell you from experience that Toyota corporate will come up with a solution (if one exists) once a certified letter arrives, informing them of an impending Lemon Law claim.