Accelerator Pedal Sensor problems of the 2011 Subaru Forester

This happened while driving through colorado, from crested butte to telluride. I was driving with the cruise control active. As the car went up hills it would automatically shift down, causing the engine to rev into the 4,000 rpm range, which is not safe to drive sustained. In order to combat this I used the manu-matic system to hold the transmission in the higher gear. After a while my check engine light came on. Concurrently, the traction control indicator light came on, and the cruise control light began blinking. Thinking it was an overheating issue, I stopped the car and waited a while. After a few cycles of drive/stop/drive/stop, the lights turned off. Thinking the issue was resolved, we continued on to telluride. Leaving telluride, however, with the same driving behavior, the issue returned, only worse now. When the lights came on the accelerator stopped responding. We were headed uphill at 65mph on a narrow two lane road, with a steep drop off the side, and multiple cars behind us. I pressed the accelerator all the way down and the car did not respond at all. This caused us to begin rapidly decelerating, which was extremely unsafe given the conditions. We pulled over and turned off the car. After a short while of sitting on the side of the road, I turned the car back on and the issue had ceased. The intermittent nature of this issue is scary - at any moment the accelerator may cease to respond, potentially causing a life threatening scenario. Upon reaching our destination, a friend had a code scanner and pulled code "p2138 - throttle pedal position sensor switch d e voltage correlation. " there's no official documentation from Subaru, that I could find, on the issue, and browsing various Subaru forums turns up a lot more questions than answers.