2016 Kia Soul multiple codes all at once, P0456, P0335, and P0456pd. Please help.

My serpentine belt was going, I ordered a new belt and went to work the next day. On my way home, my console popped up a message and said that my engine control system had a problem and that I should get in to a dealership. The check engine light came on too. The codes it displayed were P0456, P0335, and P0456pd. I changed the belt, and it had no effect on the error codes. I changed the crankshaft sensor and the message on the console popped up again when I started the car, and it didn't change the error codes. My car doesn't smell like gas at all. I checked the sensor fuses and they are fine. My gas cap is also fine. The car is now occasionally stalling for no discernable reason when I'm driving. It hasn't happened when I was accelerating or driving over 35 miles an hour or Idling. Does anyone have any ideas?

Also, starting in the summer, my car started occasionally having a hard time starting and when it did start it would say I had a problem with my foreword collision system. If I turned off the car and back on the error would usually clear. I haven't had the problem for a while, but I just did a few days ago. I'm trying to avoid going to a mechanic because I can't afford it. Thank you.