Subaru Limp-Home P2102 Case Study - Part 1

The owner of this Subaru Impreza had been chasing a very strange intermittent problem for months. In fact, the previous owner got rid of the car because he could not figure out the problem!!
When he starts up the Subie on a cool morning, it often goes into "limp home" mode, setting a P2102 DTC. However, if he starts it up in the afternoon, car runs great. Once it warms up, it will drive fine all day long.
He already replaced the Throttle Body and a relay, took it to several shops, all to no avail. It's time for Pine Hollow Auto Diagnostics to take a crack at it...turns out to be a great case study.
Enjoy!