left front brake hanging up

I hope some Ford dealer technician might know the answer to this. I have a 2001 Focus LX. I've noticed that the left front brake has been getting hot and hanging up intermittently.

I notice an odor from the LF wheel and if I jack it up the wheel can be turned but there is definitely some drag on it.

I've already replaced the LF caliper and brake hose. What's next? Do the master cylinders have problems? Brake booster? I don't understand this, and I have been a mechanic for 20 years.

By the way, 124,000 miles, no ABS. Thanks!

Is the rotor warped in any way? Only thing I can think of, but I'd think that you would have thought of that already...

Also, sometimes it sounds like a metal-to-metal brake sound when applying the brakes. I thought I was metal-to-metal, and I bought some pads and took the brakes apart and everything looks perfect. (except the left side is wearing faster). I also clean and lube all the caliper slides and bolts whenever I've had the pads off.