I don't f'n beleive it!! I change the spark plugs in my truck to the colder ones. After I get them changed, I take the truck for a spin to see if it affected the A/F at all. Well before I even get out of the sub, I feel that there is quite a hesitation. So I pull over pop the hood and check all of the sparkplug wires. Well what do you know, one of the wires was not conected. Well I pop it back on and fire up the truck to hear a nice ticking sound from that plug that grew louder to more of a sputter. It almost sounds like a bad maifold gasket leak. I pop the hood again to feel a nice puff comming from between the front spark plug on the passenger side (which was the wire that was not hooked on in the first place) and the header. I shut the truck off again and get a little burnt oil smoke comming from the header gasket area and imediately throw out a pronounced F bomb. So it sounds and looks like a cracked head to me, what do you guys think? If that's the case what should I do? How F'n stupid is this that I break something before I even hit the spray. I still don't beleive it!