The fact that it happened so suddenly, I would agree that a misfire is what is most obvious. It could be a vacuum leak but that would not necessarily cause the smells that you were experiencing. That points to unburned fuel in the exhaust as you stated. The only question is, what is causing the misfire. So sudden like that I would think it is something that affects all cylinders rather than a spark plug. The only reason is, it sounds like more than just one cylinder.
All that to be said, I would be interested if there are any DTCs in the computer. That will point to what the issue is. Could be a Mass air flow sensor throwing off the PCM but that would most likely turn on a check engine light and you didn't mention that being on. If no check engine light, I would think a vacuum leak explains everything except the smells.
Feel free to run what your service shop says past me to see if you want a second opinion of what they say and if it makes sense. Thanks
Friday, April 19th, 2019 AT 3:05 PM