Good long lasting spark plug?

[Mustang5L5]

Nope not here.

If it's vibrating when you let off gas, i'd take a serious look at your u-joints or your transmission tailshaft bushing. I don;t think it's engine related at all

 

[salstang]

NGK or Denso Iridium gets my vote

 

[Mustang5L5]

NGK or Denso Iridium gets my vote

Iridium, Great for boosted apps, waste on N/A.

 

[98blackstallion]

Iridiums are good for F/i? Ive been told that they were bad for F/i???? Im thinking of going with either some autolite platinums or motorcraft platinums?