Robert Your system is way out. Something is not working at all. We really need to know CO reading and the CO2 reading to better pin point fault but I am guessing that the O2 sensor is not working or the Lambda circuit is shut down; especially if you got descent spec readings 12,000 miles ago. The system is probably "rich" which the default condition for an O2 sensor failure. If the frequency valve is not working the lower chamber pressure in the fuel distributor has probably increased also causing a "rich" condition. Spark problems do not seem likely to me. I suggest checking the lambda circuit first. That includes the RPM relay functions. The diagnostics can be rather tedious and you should have the DMC Technical Information Manual to guide you. Check the fuse, check all connections - disconnect, inspect and reconnect is a good idea to be sure everything is secure. Turn the key to run and listen for the buzz of the frequency valve. Start the car and listen for the buzz. Use a stethoscope if necessary, but it has to be buzzing. There is away to check the O2 sensor but if I were you I would just replace it. If the system has proper function the engine should be constantly hunting the ideal fuel-air mixture. The classic fast hunt - I love that sound. If you wish you can contact me off line and we can discuss further. Harold McElraft - 3354