A month ago I was driving on the highway when I heard started to hear clicking coming from my engine while I was accelerating trying to get up a hill, I noticed my CEL started flashing and I took it and had it scanned I had 3 codes. 1. Fuel system too lean, 2. insufficient EGR flow. 3. Cylinder 3 misfire detected. I had just changed my plugs a week ago and figured id done something wrong so I went back and tightened the plug on cylinder 3 and changed the wires on cylinder 3 intake and exauhst sides. Still no luck I changed my coil packs as well. I am completely out of ideas. Maybe the plugs werent gapped correctly? They were motorcraft plugs I put in. I have a video of the noise it makes and I would like to share it with you guys to see what you think it is

Looking into it more its called spark plug knock. Anyone have an experience with that? Its a 2.3 liter. I looked at the piston it had quite a bit carbon build up. Also I replaced the timing belt and they say it could be messed up valves too.