Car Will Not Start problems of the 2006 Subaru Outback

My fiancee was driving my 2006 Subaru Outback on the highway approximately 65 mph when there was a sudden loss of power. The throttle was unresponsive, but the engine remained idling. My partner pulled over to the side of the highway and tried restarting right away but the engine wouldn't start. After waiting a few minutes he was able to restart and drive normally. The cel was on with the cruise control blinking. When I took the car in to get the code read it gave the p2138 error code. In the last month this has happened 3 more times, including when on the way to the mechanic this morning. The mechanic said he has heard of this problem previously with '06 Subarus and recommended I get the wvu31 recall update, which I am really hoping will make a difference. This is extremely unsafe and essentially makes my car undriveable as I am never certain when a sudden loss of power will occur. If this happens where there is no shoulder it could easily cause an accident. This is an extreme safety concern that needs to be addressed!.