I had to remove my cat converter to work on my trans a few months ago, its a 91 2wd automatic w/2.3 eng, it was in bad shape so I got rid of it and used flex pipe. The truck runs ok and has new plugs /wires/ fuel filter/air cleaner. but now is getting only about 12 mpg it was at about 17mpg 6 months ago. I know theres a co2 sensor just before the cat and that sends a message to the computer for more or less gas, I am assuming that now it is cooler at that point and the computer thinks it needs a little more fuel, I disconnected the sensor and she ran ok , but the exaust smelled a little different so I replaced it, is there anyway to bypass this sensor, I already spent enough money in this truck, she just a get-er-round truck but all I have.