Greetings. I have been reading posts and was hoping someone could give me a little help. I just bought a used 97 850 2 weeks ago. The dealer I bought it from is being very helpfyul, but I want to check on a few things to make sure I am armed and ready when dealing with them. The prolbem 2 fold. First off, the gas mileage seems to be rather poor. Secondly, I have noticed when accelerating, there is black smoke coming from the tailpipe. The check engine light has come on and I am getting ready to take it in to the dealership. I just want to be prepared to answer and ask the right questions. Any help would be greatly appreciated.