Overheating after Thermostat Change out

id take ur rad out and pour clr in that ***** plug off the holes and shake it somehow so it will dislodge the crud and clean it! could work and save u from 200 on a new rad. then id run some rad flush when u reinstall it run it with clr and try to clean inside engine and drain and refill with nice new antifreeze i even go and put in the antifreeze prestone conditioner and waterwetter