TPIini Tom couple of things Unless you are running FI where the computor is adding and taking fuel from the motor, you are not going to get an accurate reading. The reading will change by you pressing the gas pedal. If you run rich for a short time you will foul out an O2 sensor and it will lose it's ability to work properly. A wide range O2 which I have in my Speed-pro system works great. There is no heated O2 sensor but putting the sensor in the best place for the most accurate reads is 6-9" after the collector. The sensor as to reach 600F before it starts to work. Some race gases and additives foul out the sensor and give wrong readings.You should get an EGT module with 2 sensors to check both banks for them both working around the same temp. Low temp means too rich,high temp too lean. Then compare it to your A/F ratioand make adjustments from there. A good A/F is $400.00 min with a wide O2 sensor. You have to weld the bung into the exhaust, EGT sensor can be clamped on to the exhaust pipes. By running the motor lean NO MORE THAN 1 MINUTE, this helps clean the O2 sensor ( operating temp) Make sure that any carb cleaner or FI cleaner is O2 safe. If not it will leave a film on the O2 and wrong reading. Bosch makes the best after market O2 sensor but with factory FI system go with the factory one for that system. It's like putting Autolite plugs in a GM motor. It runs OK but not right.
Good luck Rick Lake