new rear drum brakes pulsate 2001 Jeep cherokee

I have a 2001 jeep cherokee and we just replaced the rear drums and shoes. About a week later the rear brakes began to pulsate. They do it with the e-brake too and in neutral also. This is only when the brakes are on. These were cheap brakes and drums. It almost looks like the shoes are vibrating (slip/sticking) against the drums. Is that possible?

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