Toyota Repair: 1997 Toyota Camry Front End Vibration, front wheel bearing, front end vibration

Question
I have a 1997 Toyota Camry LE 4cyl automatic with 140,000 miles. Whenever the car is accelerating from 45 through 60 mph, their is a very pronounced front end vibration. I had the tires balanced-no change. Bought new tires-no change. Discovered bad driver front wheel bearing and had it replaced-no change. Had new tires re-balanced-no change. I have been able to discern that the vibration stops when I take my foot off of the gas. When going down a hill with the transmission in nuetral and the car accelerates from 45 to 60, no vibration. I have even replaced a rim that was slightly warped to no avail. My mechaninc has rechecked the bearing and it is correctly installed. Tires have been checked several times for defects, non exist. There is no evidence of drift due to alignment. I am at wits end. WOuld you have any suggestions on where to start to look. I have so far stumped the technicians on this one.

Thanks for your help.

Answer
Possibly a drive axle problem, this is usually caused by a worn inner CV joint, start by replacing the left side drive axle, or have them both checked to see which one is causing the problem, you may end up having to replace both the drive axles to resolve the problem.