Old Ford disk brakes

I have a 1972 Ranchero, and I'm having problems with the stock disc brakes on the front wheels.
It's not that they're seized in place, but they just don't release fully, so whenever my foot is off the brake pedal, the brakes are still slightly engaged, just enough to notice the car decelerating a little too fast, and if driven to long you can smell the brakes overheating (I only did it once).
Now, I've already bought a replacement set of stock calipers, put them on, and it's still doing the same thing. I was told that this was actually a common problem with old Ford disc brakes, so I decided to come here for consultation.
Does anyone know if this indeed was a common problem?
And does anyone know how to fix the problem?

Crack the brake bleeders open just a little and see if there is any pressure built up in the caliper.
If so check the front brakes hoses for swelling up inside and holding pressure on caliper.
Also sometimes a master cylinder or the adjustment can hold pressure on brakes.
Another thing you can do is leave the wheel bearings a tab on the loose side. That helps kick the brake pad back off some.
MT-2500
MT-2500

Also check the master cylinder and proportioning valve. Either of them can have a check valve "hang up", preventing the pressure to return to resevoir.

Correct "adjustment" for front wheel bearings with disc brakes is .005" clearance (cold). Use only disc brake "rated" wheel bearing grease.

Jim