Longest time you left your Yaris engine running

[sidewinder]

Do not worry about damaging your engine, with it idleing for 1.5 hours in temps that low. The worse thing that you probably did was build up a little bit of carbon deposits. If you ran the car every day idling that long you could clog your cat converter.Take it out on the highway and clean it out a little bit.
I have worked on engines all my life, every thing from car engines, diesels, to jet engines and as long as your cooling system works properly you won't hurt the car. With the extra cold weather we get in New England, you need to properly warm your car up. Today was 5 degrees out and I warmed mine for about 5 minutes before driving off. Good luck with your car and put your mind to rest.