new rear brake pulse

I replaced my rear drums, pads, cylinders, and springs that came in the kit. ever since when the brakes warm up they pulse. They work well but shake the truck sometimes but not consistently. I also bleed the brakes properly. The wheel does not shake so I am pretty certain that it's the rear brakes as it started immediately after I installed new ones. I have removed the drums twice now and inspected, cleaned, and adjusted the brakes. They are the same. Thoughts?

 

I can't tell you how many people on here have bought aftermarket brand brakes and had the exact same issue. It's been a hell of a lot. I've never seen that with people who bought OEM drums. Drums were warped, right out of the box. Multiple different store brands.

What brand did you go with?

 

Duralast from Autozone
How do I check if they are warped if they are on the truck? It is my only transportation