Another thing that can cause rotor warping...
...is the use of an impact wrench to tighten the lug nuts. Often, they overtighten, and can actually warp the rotors. And loosning the lug nuts after they have been overtorqued won't make them go back to their original shape.
Also, the thinner the disc, the easier it will be for it to warp. So if you have a set of discs turned down, they will warp easier than the first time.
I have 97,000 miles on my 1995 LX V8 and I am on the original rotors, and I only had these cleaned up when I replaced the original brake pads at 87,000 miles. They are smooth and there is no warpage. I can't explain why.
Yes, the 1996 & 1997 T-Bird Sports came with larger disc brakes and 16" wheels to clear the bigger brakes.
You can always swap a set of Sport brakes or Lincoln Mark VIII brakes, but then you'd probably have to get a bigger set of wheels. But, that could be your excuse to get new wheels.