I have a stock 88 GT. In recent years I have dealt with erritic Idle problems, caused by either Vacmum hoses or PVC tubes. I have cleaned the throttle body and for the past year or so everthing was good. warm Idle was around 800 rpm. Recently the Idle has started staying around 1400 to 1500rpm even when the engine is warm. The Oxygen sensor has never been replaced and I have one not yet
installed but I'm not sure this will correct this? Has anyone else had this issue? Could this be caused by the TPS sensor?