slightly pulling left when braking 92 chevrolet 1500 pickup

92 chevrolet 1500 pickup
recently I noticed my truck started pulling a bit to the left when I brake slightly and its done this before when I needed to change my brake hoses but this "feels" different. Whenever I am going slow and brake I can look at the steering wheel and see it slightly turn to the left and I can slightly feel the braking in my steering wheel if you know what I mean... I only notice it when going slow and braking like when coming to a stop sign. Recently changed the front and rear brakes, but I didn't notice this problem directly after that, problably a few weeks later. I do recall one of my wheel weights falling off one of the front tires a little while back but I figured that surely wasn't my problem.

Any help would be much appreciated. may need to resurface rotors,also make sure where the calipers slide on the spindle are clean and lightly lubricated Still doing it...

I should have added that the brakes are all new, new rotors, pads, calipers.

Bled the system to make sure there was no air in the lines.
It happens when I push the brake not when letting off, so I am quite positive it's not a caliper sticking.

any other suggestions would be much appreciated.