Clicking noise and shuddering?

For several months, it has been making a clicking sounds from the front driver side wheel area when I make a sharp left turn, usually only when accelerating into the turn. I took it to the dealership and another mechanic to check the CV joint, and neither could get it to make the sound when they test drove, and neither found anything wrong with the joint or axle. The car also now shudders when I am accelerating uphill, usually at a higher speeds such as over 50 mph. By shudders, I mean that the steering wheel wobbles, and the entire car feels like it is shuddering. I haven't noticed any noises with the shuddering except for the obvious increase in road noise. Any ideas? They did mention that I have an aftermarket front axle so I think it has gone bad I need to replace it.