Front brake pads will not release

Check the rubber brake lines, when they go bad they can keep the brakes applied. Another thing can be a bad master cylinder, the internal check valves are not releasing pressure.

Original calipers may be defective. Check: Calipers guide pins (they) could be bent, seized up or twisted out of shape, typically as a result of the effects of heat that you may not notice it at plain sight. Do not drive it until problem has been corrected. thanks!

I had also cleaned & lubed the caliper guide pins, and the calipers do slide by hand. And the rubber brake lines are new also. I have not removed the piston from the calipers to replace the o-ring. So that might be the cause? Or the master cylinder / booster. I've never worked on either, so I don't know how they disassemble or what to do.

You need the right tools to rebuild the calipers so most opt to just replace them. If the master cylinder is stock then that is also suspect.

The brake hoses can collapse internally so you may not notice .

is it happening at all wheels?.., whatever the answer was then check: Power Brake booster integrity_Check Valve and Vacuum chamber, Diaphragm, Pushrod adjustment, Operation and Air-tightness check. Master Cylinder_Primary/Secondary rubber cup, Return spring. Pressure regulator valve or HCU electrical connector and wiring. Brake lines and hoses. Single-piston Caliper_piston, piston seal:may be defective/malfunctioning, dust boot. Not sure thou but you may consider using brake pad support plates or brake shims. not being seen on picture. thanks.