Question

1996 Chevrolet Impala SS 5.7L with engine code P0101. I replaced the sensor and wiring harness. ...plus checked the vacuum lead. Replaced leaks...cleaned codes....came back

Answer 1

P0101 Mass or volume airflow circuit range / perfromance problem

If the code returns , is there any EGR code that appears. or any EVAP purge code with this? The solenoid of the EGR and the EVAP purge are on the same circuit. If there is a rough idle that could also be the result with the MAF (mass airflow) code returning. a slightly open EGR valve or shorted EGR solenoid can set a MAF code and so can low fuel pressure, The code condition you have is a performance issue if there is a rough idle which affects the perfromance of the MAF.

Answer 2

P0101 Chevrolet Code - Mass Air Flow Sensor Performance
Read more: https://www.autocodes.com/p0101_chevrolet.html