Spark Plug Blown

My 93 Bonneville is running terrible I changed all the plugs and wires in the proses i found a bad spark plug the porcelain part was like burned off so i thought no big deal change this plug and ill be ok but still running bad anybody have any suggestions

Welcome to AF. Check compression in all the cylinders to determine the engines basic mechanical condition, focus on the cylinder with the bad plug first. Also make sure you have the right wires on the right cylinders.