Shifter cable trouble

I changed shifter cable on the car, it worked perfectly for a few days. The cable begin getting tight again and broke the shifter handle. I replaced the cable with a new one again, and the shifter with a used one, now it’s starting to feel as though the cable is dragging, is the best way to describe it. What would cause it to feel like it’s going to do it again? I’ve done all this in about 2 weeks time. Is there a way to lube the cable that’s been installed? Any help would be appreciated!