My 240 has been handling badly for a few months, I initially thought it was a tire balance/pressure issue, but after making sure the tires were good I am still having trouble with staying steady, especially at higher speeds. While driving on the highway it feels dificult to stay in the lane, and changing lanes is sloppy. There is some slight vibration in the steering wheel but nothing crazy. First thing that came to mind was a bad ball joint, but my mechanic had the car over the weekend to replace the timing belt (just don't have the time ) and he said the front suspension/steering is fine. (I don't believe him)
Any suggestions?

Thanks in advance!! I am installing IPD swaybars off a junker and also ordered a lower strut brace so I am looking forward to having a car that handles like a volvo again

 

I would get the front of the car on jacks so someone can move the tires left and right while you inspect what is going on. It might be the u-bolts that secure the steering rack to the cross member are loose.

 

Thanks I will give that a try when I'm putting in my front swaybar.