NHTSA Complaint #11512511 — 2018 LINCOLN MKX

When I utilize my ac or heat without pressing a certain button after a while I start smelling a burning smell coming through the vents. When I'm outside the vehicle I smell it as well. The smell is hard to pinpoint. A dealership told me that maybe I needed to change my air filters. However the burning smell still would happen just the same. Then they checked to see if anything(such as plastic or anything) was stuck to any components that get hot to no avail. But something is wrong and it's scary. Also my vehicle has a very rough idle which sometimes can feel like a rumble. A tune up was suggested and complete and I still have the same experience. I love my vehicle but growing tired.