I have a 2022 Duramax L5P with 34000 miles. I recently took it in for a transmission recall and ever since, the truck has had a lower fuel mileage by gauge only. Usually when I let off the accelerator, it works its way up to 99 MPG, now it only goes up to right around 70 MPG. Also have a burning smell that reminds me of a regen when I stop and get out of the truck. Also another question. When I start the truck up it automatically goes into high idle situation!