Sharing my experience and fix for a vibration while accelerating. 2007 ES350 with 126,000 miles. There were four vibration symptoms.
1) Accelerating uphill in the 40-45 mph range. Vibration was somewhat noticable in the steering, however the entire vehicle would shake.
2) Slight vibration at speeds above 70 mph.
3) Vibration would get worse as the car warmed up.
4) Vibration while braking to a stop that could be confused for a warped rotor problem.
Lexus dealer went through a series of checks/tests. Inspected motor mounts. Road force balanced tires. Replaced tires/wheels with test/wheels. No issues found with any of those tests isolated the problem to the passenger side drive axle. The CV Joint closest to the transmission had a split rubber boot, was slinging grease and the bearings went bad. Replaced the entire passenger side drive axle and all vibrations are gone. Lexus dealer quoted $1200 to do the job. (Really?) Goodyear Service got it done for $400. All is well!
