2003 Chevy Malibu Rear Brakes

Hello. Been having problems with this car since the day I bought it. For the past year i've been experiencing a pulsation when I apply the brakes. It's a 2003 chev malibu LS. The front wheels are caliper type brakes and the rear are brake shoe type brakes. So far everyone I talk to has told me to change the rotors and that should solve the problem. Well on saturday, I went ahead and changed both front rotors, both front calipers and both wheel disc pads. I used that silver colour anti stick brake lube to ensure all parts move freely. The front brakes are working fine, but that still didnt solve the problem. On sunday I went ahead and bought brand new shoes and drums for the back and put them on mself. I used the same silver colour lube also ensure parts move freely. Additionally I went ahead and replaced both rear cylinders just incase. Problem still not resolved. I tested the parking brake, it works fine. But I wanted to see what would happen if I apply the parking brake while driving around 15kmph. When I applied the parking brake, the passenger side rear wheel kept making a knocking noise. It's as if the brake shoes are attempting to grip, but keep slipping and banging on something. All parts were secured and I set the parking brake before putting on the drums just to ensure everything worked smoothly. I dont know what else part to change in order to fix this problem? Can anyone help?