Check your Oxygen or Air Flow sensors. I recently had the same problem with an Outback. Every time I went up or down a hill, made a sharp turn, or accelerated, it would stall. I found a broken wire on the Mass Air Flow sensor. Replaced it and now it runs just fine. Good Luck.
I would do ^^this^^ before swag-ing out the ECM.
Winter rusted, corroded or broken electrical connections and dirty or worn out/broken sensors seem like better, cheaper guesses.