07Legacy666

So I recently purchased an 07 Legacy. Great shape, lowish km's, seems to run just fine. Except for when I took it on a long road trip through the mountains. I would be givenr hard 100-110kms on an ascent and all of sudden it felt like the drivetrain would slip or something and the engine or tranny would start hiccuping, like I'd have the pedal down and it would just lose all power and start jerking like it was gonna stall. The check engine light came on as well as the cruise control indicator started flashing. I kept going on to my destination and then also the return trip, where it happened again. Total kms were around 1600. Wtf? Anyone experienced this?