In the 2013 5.0, were Platinum or Iridium spark plugs stock? I just had mine done today at 80,000 miles and the shop owner called me saying he pulled Iridiums out. His book shows Platinum are supposed to be in there and that's what went back in. He said the Iridiums looked good, engine is burning great, but gap was huge. I bought the truck as a certified used with 27,000 miles on it. Maybe the dealership did a tune-up prior to selling it? Thoughts?