What kind of transmission do you have on that car(manual or auto)? is the check engine light on?did you run a scan?what sensor did you change? i'm suspecting you might have an rpm-related vibration say like to low idle running.or it might be something from the transmission,try put it in neuyral when slowing down.
If your vehicle suffers from an annoying vibration, take it to a reputable mechanic. Have them test drive the car. They should be able to diagnose the problem and recommend a solution for the problem.

naturally toyota/lexus transmissions are not as temperamental as nissans.you may ask your technician run a diagnostic scan on the transmission of the vehicle,and a test drive as well.

great job peeps
vibration at top speed could be caused by a number of factors
1-alignment
2-balancing
3-bad suspensions i.e shocks,linkages,ball joints
4-steering components
5-tyre bulge
6-bad rim
7-worn egine & or transmission mounts
your technician needs to isolate the problem, moreso you have done alignment&balancing check from a reputable tyre center