While driving my rover this cold winter morning, as I was coming to a stop she decided to just stop running. The engine RPM just slumped until there was nothing. Fortunately, when I tried to start her again, she fired right back up. However, as I was driving, whenever I took my foot off the gas, the RPM would drop down around 300-400. Eventually this normalized, and when I pulled into the parking lot at work, she was happily idling right at 700. I have also successfully restarted her after letting her sit for a little while after I got to work, and everything seemed normal.

Has anyone ever had anything happen like this before? What might be causing this?

Some other information about this incident: It was about 5 degrees outside, and the engine cut out happened a little over two and a half miles into my five mile drive to work. The idling RPM had normalized back to 700 about a mile and a half later. She also threw P0125, the warm up time out code, shortly after I started my drive.

Thanks!