I recently removed and gapped my spark plugs, in reinstalling the fourth one I managed to cross-thread the hole but no worries I retapped it and the plug seemed to go in fine but the nut on the plug wasn't tight enough to be touching the cylinder head even though the plug was pretty snug. This also seemed to be the case with the other plugs -snug but there was a gap between the head and the nut on the plug. Additionally, the car sounded strange and I had a very noticeable power loss and so I think maybe the plugs aren't as far in as they need to be so the whole cylinder doesn't combust all the way which is why my exhaust sounded different and I lost power. Any suggestions? The plugs seem good but maybe I should just get new plugs?

 

The "nut" shouldn't touch the head, there is a space between the sealing washer and the nut. What were the original symptoms that made you want to gap the plugs? How many miles on them?

 

what kind were in there? i removed some denso's that were pretty crusty... suggest replace with bosch or ngk's

 

If the "fourth" plugs fits the same as the other three, then there shouldn't be a problem...
Is there any compression leak from the crosstreaded one? That, would make a difference.