2014 Scion XD misfire cyl 1

[Jodysbusyagain]

In April I purchased a 2014 Scion XD with 11k miles on it. The vehicle is salvaged due to a front end collision but frame/engine and etc are all fine.

On the drive back from Vegas to Iowa, the vehicle chugged a time or two, the check engine and track lights appeared. After restarting the car, all was fine and drove like a dream.

Since then on several occasions, the check engine/track lights keep coming on after being reset. Each time the code returns a cylinder 1 misfire. Now I've noticed the 'rotten egg' smell like a plugged cataletic converter smell...

Anyone have any suggestions on what it could be? It only has 20k miles on it....

HELP!
Thank You