2001 Aurora wobbles only on acceleration 40-55 mph

Help - our mechanic told us we had bad belts in our tires, and we should replace them. So we did. Over $500 later, the car still wobbles. It only happens on acceleration, and it starts somewhere around 40 mph, gets worse as I drive faster, and then around 55 mph it goes away. It does not happen on deceleration. We’ve seen posts on other pages where people have replaced CV joints, both front wheel bearings, both axles, tie rods, control arm bushings… but that doesn’t solve the problem. Before we go spending another $500, we’d like some solid answers. Help?

Just to clarify, let’s say you’re going along at 50mph. If you hit the gas a bit to accelerate it will start to wobble? But if you pull your foot off the gas the wobble will go away pretty much at the same time? If that is true then this is most likely to be found in issues with motor / transmission mounts or a problem with inner CV joints.