hi everyone,,
I have a 2007 grand marquis,,, same as crownVic,, its a 4.6L stock engine.
I'm getting a misfire code cylinder 5 and 6 and I wanted to replace spark plugs first, since they're old.
Would my best choice be motorcraft SP405 fine wire platinum or SP493 standard platinum ?? or is there a better choice.
Any help with misfire also appreciated. Thank you

 

I would suggest sticking with standard Motorcraft plugs listed for your vehicle for now, because if it is something other you just sank a lot of $$$ when you didn't have to.