I own a 2009 Ford Expedition and I started having transmission problems and I got my engine light on. So I took it to auto zone and they said it was a 5 gear incorrect ratio. I thought by changing my fluid and my filter it would help. Well when I took the fluid out and I seen that the fluid was really black in color. And it also had a really bad smell to. I started the car today and I go to put the car in reverse it goes forward. How can I fix this problem?