I finally discovered what that vibration was in the left front. I thought it was cured since it went away with the change of wheels and tires, but it returned. I thought it was the left front caliper sticking or perhaps the ABS acting up. That wheel did not spin freely....all the time. Applying the brakes revealed that the caliper was sticking badly, and had been destroying the wheel bearing. The rotor was not so great either. These were all the original parts from what I could tell, so 130K miles was not bad. The whole job took almost 7 hours due to the inadequacy of my paltry tools for this behemoth.