OK, I guess I'll give the full story here to make trhings a little clearer. First, I am an extreme perfectionist. I hear things and see things wrong that normal people don't. This time may or may not have been an exception.

I bought this truck about a month ago. It is a 99 5.4 with 56000 miles. Its hot here in TX, so I normally have the A/C on full blast. I was driving the other day with the blower speed low and noticed the engine seemed noisy, and would ping under a load. I have done countless searches on this board and found it to be a fairly common problem. I ran a tank of premium to see if things got better, and they did. Pinging was still evident, but not as severe. I then proceeded to replace the fuel filter and run some Chevron Techron cleaner in the next tank of gas. I filled up with 87 octane this time. Two days later(today) my uncle, who is an excellent mechanic, was visiting. I wanted him to go for a spin with me in the truck to listen to the pinging and see what he thought. I started the truck and we were about to leave but something was obviously wrong. The truck coughed and sputtered upon startup, and was shaking badly (first time it had ever done this). He immediately dignosed it as having a dead cylinder. Our thinking is that the motor was pinging due to excessive carbon buildup. Running the Techron treatment loosened a piece of carbon and got lodged in one of the plugs. We will be replacing the plugs at the first possible chance (hopefully tomorrow) and I need to know what to buy. I know I want to go with Motorcraft, but can I get these through Pep Boys, O'Reily, etc? What plug model do I need? If all goes well we will get the truck running properly again, and then go from there. Probably will de-carbon the cylinders to get rid of the pinging. I understand that the dead cyclinder could be any number of things, but most signs seem to be pointed towards what I described and it seems a good place to start. Any advice is welcome, and if anyone could tell me what plug I need it would be a great help.
Thanks,
Brian

 

just go to the dealership and get the plug numbers u need also any cel? maybe try switching the coil form the bad cyl to another one and see if the bad cyl changes... if so u need a cop replacement

 

We need to find out which hole ain't doing it's job first before doing anything else. Is the CEL on and/or flashing? If so, tote it down to AutoadvancepepboysO'Reilly'sZone and get the codes pulled. If not, start disconnecting coils at idle, whichever one you disconnect and the idle doesn't change, there's our dead hole.