Hi everyone. Thank you for your help. Definitely appreciate it when I'm freakish out over this issue. I have an update to the situation:
Like epapp said, we ended up finding out that one of the rollers was bad by taking of the belt and inspecting the pulley. We ran the car with and without the belt to confirm it. On that note, I left his house and drove to the airport and then home, at total of 100 miles. During the drive, the check engine out came back on (I expect the computer fully reset itself) and it was the same p0343 code. I cleared it again and drove home as carefully as I could. To give you an idea of how cautious the drive was, here is my mpg on the way home
Anyways, When I got home and backed the car into the driveway, I heard some pretty concerning noises from the back of the car as I entered the garage. I usually take advantage of the echoing garage to inspect my car every time I pull in, so I know this was a new sound.
I took a couple sound clips of the car in the garage at idle to get everyone's opinion. The new sound is the rhythmic train track sound.
The first sound clip is of the car right next to where the engine and transmission meet.
LINK:
https://soundcloud.com/user855740199/between-engine-and
The second one is right behind the transmission between the muffler.
LINK:
https://soundcloud.com/user855740199/behind-transmission
Thank you all for your help. I don't think I'll be moving the car from the garage unless it's on a flatbed or confidently repaired.