2011 Ford Fusion Sport, there is an extreme vibration when accelerating, very noticeable around 3500-4000 RPM. Gets worse and almost turns into a clunking when you let off the accelerator especially when you lay into and to pass someone. New brakes, new wheel bearing, new tires and full rotation and balance. Please help
If you have not checked the obvious, make sure all 4 wheels are bolted down tightly.
If the check engine light is not on, I’d suspect a CV joint or entire half-shaft is coming apart very rapidly. If you can get under the car reach up and shake the axle shafts on each side. They shouldn’t be loose.
If they check engine light IS on, get the codes read and post the codes here and we try and work through your problem.
Vibration can be engine or trans problems, not necessarily suspension problems. any dashboard warning lights?
There is AWD on some of these. Check driveshaft and u joints also.