I am having trouble with my 03, 5.7 hemi misfiring. I have had it to my mechanic twice in the last month and on top of what he did I replaced the ignition wires and spark plugs about 2 weeks ago and this was the longest time with no issue since the codes originally popped. I have isolated it to cylinder 3 by replacing the coil and swapping the coil to see if the problem would move around the engine but it is stuck on 3. I am looking for ideas on how to go about fixing this

 

What kind of plugs are you using?