I have replaced 3 interior doors ( holow) with new MDF. I reinforced the jambs due to the weight on the door. That looka like iot is working. When I close the doors the last 6 inches feels constrained.. kinda like the hinges are closed but the door isn't just yet. At this time I can also see the Jambs move. I'm not sure how to fix this?

Check that the hinges are flush with the surface of the door and the jam. Not recessed in the mortises.
Check that the door is not rubbing against the door stop material on the hinge side. This is the most likely problem.