Cadillac: Brakes, pressure gage, proportioning valve

Question
i hae a 98 deville since new we have had problems with the rotors warping
the dealer turned them 3 times while under warranty because of this and told us this is normal i have worked on cars myself for nearly 40yrs and never saw this before
Now i hae replaced both calipers and rotors and flexbile hoses but the calipers still drag slightly enough to make noise
it has a ABS system on it also which i am not familier with the only things left on it to replace as far as i know is the brake booster and master cylinder
WHAT do you think the problem with this car is other than the brakes making a squeeking noise we love the car but this has driven me up a wall since 1998
thanks
gordon

Answer
At this point I would put a brake pressure gage into the system with  with enough tubing that you can monitor the brake pressures as you drive it on a daily basis and see if you are getting an intermittent high pressure reading when the brakes are off. You may want to take a look at or replace the proportioning valve.