(ref: 04 Lincoln Town Car Signature bought used in Feb 07 w/36.5K miles, now 44K miles)
For the most part it turns out that the rear suspension was too high (I always wondered why it seemed a little jacked up in the rear and have seen other TC's look the same). Now the rear of the car looks lower and almost parallel with the ground. The front is at the same height. The advisor says when they forget to turn off the air suspension before raising the lift and the wheels drop all the way down, the system looses calibration.
On the invoice: "Road tested vehicle with customer and verified concern. Tech road tested and confirmed vehicle unstable. Inspected F & R suspension, check VAPS at rack and pinion. Checked OASIS - No known concerns. Torqued all suspension bolts and performed air ride suspension self test - pass. Performed air ride calibration - calibration normal. Set all tire pressures to specs, performed alignment with 4 wheel runouts and road tested vehicle with advisor. Vehicle handling normal. Note vehicle has aftermarket shocks (4 KYB shocks)."
This took care of about 80% of my complaint but I would say the other
20% of what's left is me focusing on what is probably typical handling for this car. Perhaps the sidewalls may have softened a little but the tires seem OK except for the one that leaks slowly only during driving. It's now considerably more stable and easy driving on the highway.Ben