I have a white 2004 Ford F-150 4x4 XLT Screw. I bought it new in 04 and have not had a minutes trouble since I have owned it. (Knock, knock on wood). Just put some Mickey Thompson 12.50 on my baby. Just put some dual FlowMaster exhaust so I can make her more efficient and perform a little faster. I also just added a Spectra cold air intake on it. I am fixing to purchase a Hypertech programmer, if this will help? My brother has an older Ford Mustange LX 5.0 in which he installed some under drive pulleys and a flex fan. Can these be added to my 04 Ford or leave this alone? My girl has about 160,000 miles on it, and has never had the plugs changed. It does not skip or tap or anything, so I have not changed them out. However, I did call our local Ford dealership and they informed me of the spark plug issues and said that it could possibly cost me 1000 to replace. I said F that. I don't know if I trust my brother the "shade tree mechanic" or myself to do this job. However no way I pay this much for a plug job. Also, when I had the FlowMasters installed, the Cats were untouched. Can these things be removed? I know these things have to be clogged up. No telling how much power I am losing with the plugs and converters. The back bench seat is a pain in the a$$, but I have dumped enough on everyone. I am proud to be here and look forward to reading all post from fellow F150 enthusiasts. I love my baby. I think my GirlFriend is a little jealous of her....LMAO!