2005 grand caravan thumping noise aat very low speed

Dealer replaced rack,twice. Still thumping,they installed new struts and 4 sway bar links and bushings same thump still there. I unhooked swap bar links and tied them to brake line and backed it out is my shop and thump is still there and sounds like both sides. This van has 56,000 miles on it and the ball joints and control arms feel and look tight. Is there anything about how frame mounts that might cause this?

Cyclic as if something rotating or random such as over bumps or in turns.

My shop has gravel and when I pull out its a slight uphill, it is something in the suspension or at least feels or sounds like it. It sounds like a rumble but not like a wheel bearing. I shut Van off and coasted in yesterday and same rumble noise.