My 87 turbo regal is getting poor gas mileage. It runs pretty good, but I don't have any tuning tools. I'm sure it runs rich, because I smell gas sometimes, but it never knocks. Anyway, the drivers side header has a small crack on the middle tube, and it may be letting in extra O2 from outside, causeing the O2 sensor reading to be off. The injectors are green stripe from who knows where, but the previous owner put them in. Any thoughts on the topic?