Anyone have any ideas on this problem I am having? 95 Sable, 3.0, 295,000 miles on it. Check engine light comes on but never sets a code. Have driven it with the scanner hooked up and the light comes on but no code. Think I have issolated it to the fuel system. If I leave the gas cap tight the light will come on and the car will run like it is missing 3 cylinders. If I loosen the cap while it is doing this the car will start to smooth out but the light will remain on sometimes. As long as the cap is loose the car runs good but the light will come of and on, particuarly if driving up hill with a load on it. I saw a post on here suggesting that the T fitting under the radiator could be of an issue since I do smell fuel fumes from time to time. The fitting was clean but I did try to blow air through the vapor line that runs to the tank. There is not any air coming out of the tank but the air is coming out of a small vent hose that is running with the fuel and vapor line near the fuel filter. Should air be coming from the tank and not this vent line? Any ideas or suggestions would be greatly appreciated.