2006 Ford Freestyle SEL AWD: Wrench Light, Engine Death & Fuel Mileage Drop - Codes U0401, P2104, P2112

My 2006 Ford Freestyle SEL AWD has been experiencing intermittent surging issues since last summer, which began when the AC was running. The dealership cleared the fault codes at the time, but the problem persisted for months. Recently, during a 300-mile round trip, I noticed my highway fuel efficiency dropped to just 21.6 mpg. Shortly after, the wrench light illuminated and the engine died unexpectedly. I managed to restart it, but only after driving about 7 miles—this happened multiple times. After each restart, the engine light remained on permanently. I took the car to Advance Auto Parts, where they retrieved 9 diagnostic codes using a reader; six were duplicates. The relevant codes are U0401, P2104, and P2112. While the transmission shifts smoothly, the vehicle behavior is concerning. I disconnected the battery today and have not seen any lights come on since—this suggests possible electrical or software-related issues. I've already checked all accessible connections and ensured they were secure. Despite these efforts, the problem persists. Any insights into these specific codes or potential fixes for this 2006 Freestyle SEL AWD would be greatly appreciated.