I think I may have posted the following plea for help in the wrong section ( Chevrolet - General Discussion ) instead of posting it here. If ANYONE can help solve my issue please let me know.. I am lost.. Thanks in Advance.. Ok guys here is my Dilemma, I have a 1989 Chevy C1500 w/ 350, T.B.I, Automatic Trans, Mileage = High, that keeps throwing the Trouble Code 13.. I can crank the truck and drive it and it runs great BUT as soon as the engine gets warm(5 -10 miles) the Check Engine Light comes on and I can tell a noticeable difference in power (loss).. I have to press a little more on the gas pedal to maintain my current speed.. As you know a Code 13 indicates a faulty O2 Sensor, I replaced it with NO LUCK.. Could I have bought a faulty O2 Sensor? I have heard of Brand New P.O.S Before.. The old O2 sensor was white on the end if that helps any and I checked the voltage of the wire coming from the ecm with the switch in the on (not running) position and I got a voltage of 1.5volts if that helps any.. Oh and all this started all of a sudden after I done a complete tune-up on the engine. New Plugs,Wires,Cap,Button,PCV,Air Filter,Oil and Filter, New Thermostat and Gasket.. Any help would be GREATLY APPRECIATED and I am willing to try anything at this point even if it may sound odd... Thanks for any Help.