Random stall?

Scoots did something rather weird this afternoon when I made a run to town to get work shirts for my new job. After I started her and was preparing my music to go home, the RPMs dropped to about 500 on the tach, and the tach needle was real jerky as well. after about a second of that, the engine stalled out. It restarted okay, save for a spark knock like sound when the engine took over from the starter. There were no other issues on the way home. I pulled codes and found a pending P0132 and P0135. The engine was at full operating temperature when this happened, and was in park.