C.C.; Did you notice if you hold on to the intake or um you can also feel the vibration of this hum? It's a puzzle. A shop locally here felt I needed to clean the um/lm butterflies etc--and it needs it. Was hoping for the lazy man's way out--"just a sensor, or just something unpluged". By the way, my check engine light comes on. Auto Zone says replace the gas cap. Did that and it worked, but same code again later.
Mop