Is this a symptom of worn out torsion bars?

How far in are your adjusting bolts on the lower control arms? I would jack the car up so both wheels are off the ground and then back off both torsion bar tension adjusters and then keep cranking them up equally on each side. It sounds to me that you don't have enough tension on the left side or perhaps you do have the bars reversed since the left and right side bars are different. Put the weight back on the car and then keep cranking up the tension on the bars until you get good stiffness. If your suspension is bottoming that badly, you should be able to reproduce the problem by vigorously bouncing the front corner. How are the shocks? Is the left one wet and oily? Perhaps the left one has collapased?