ok then it sounds like the sensor is working correctly when you did you testes are you reading volts or mv. does the engine run bad at all. so you replaced the sensor in the exhaust pipe below the manifold then. it would be nice to know fuel trim but that is a long shot really. do you have a vacuum gauge and a fuel pressure gauge that would be a great start. if you were worried about reference voltage then you could test off of other sensors. it could be that the engine thinks it lean and it is not or it really is lean or just the opposite start with fuel pressure and vacuum. and if you do have a vacuum leak typically these older engines will idle over desired idle speed any performance issues and sorry for the list of questions just trying to get an idea how did the pintel for the IAC look