I have a 2003 Tahoe with 7000 miles on the odometer. I recently drove it to Kansas from Arizona over Christmas. I noticed it will vibrate slightly at
75 mph. One can feel and hear the vibration. I had the front end aligned and new tires put on. It did not help. The virbration is aperiodic. I mean it slowly builds up to the vibration and then slowly decreases and then increases and so on. I takes about 7 -10 seconds to go from vibration to none to vibration again. Any one else have this problem?