2000 Volvo S40 No power upon acceleration

Hello,
I was driving my Volvo up a steep hill in icy road conditions and I had a hard time getting up the hill (wheels spinning). I did not rev my motor past 2500 rpm's, then I would let off the gas to slowly chug up the hill.
After I made it up the hill, my car started running terribly. I had no power upon acceleration and could only go about 45 mph. The car would jerk forward when I stepped on the gas, and it seemed like it was trying to go but just couldnt. When this jerk of the motor was happening, my check engine light would flash.
I pulled over after I started to smell burnt oil through my air vents. Dip stick read full, and antifreeze reservoir was full with no
It has been arctic winter conditions the past week where I live, with temperatures well below zero and wind chills down to -35F.
I dont know if that is a contributing factor, just thought I would mention it.
Thank you for any suggestions before I bring it in to a mechanic.