It can be a lot, but lets try to narrow it down. Can you tell approximately where the sound is coming from? If the vehicle is in neutral and you rev it, does it make noise?
Do me a favor, take a rubber mallet and tap on the exhaust system to see if you hear anything rattling. When I read your post, my first thought was a catalytic converter issue. Sometimes they come loose internally. As a result, you can get a rattling sound, experience power loss if it moves to a position that blocks exhaust flow, and it can cause you to get fumes in the vehicle.
Let me know. We'll figure it out, don't worry.
Sunday, December 8th, 2019 AT 8:29 PM