Changed plugs yesterday, 04' 5.4, 68K miles, not an easy task. Anyway, got plugs changed, re-connected everything back up, vacumn lines, main computer, etc. double-checked everything was like before, and it ran crappy at first, rough idle, died at a complete stop. Ran a little better after a test spin, runs fine on the road, just when coming to a stop or idiling, rpm's drop to 400-600, jumping, then finally dead?? Ran it again to work this morning, it does seem a little better, didn't die at each stop, just right when I got to work? Any info?? I did disconnect the battery to see if it needed to reset itself, and hooked a code reader on it, not throwing any codes, no check engine light either, any help oout there??

 

Did you clean the cop springs and use dielectric grease in the boots?

 

Yes I did. Now the truck only idles down to 400rpm's when I come to a complete stop, dies once in awhile but not everytime. Once I put it in park, idles fine???

 

what brand plugs? look for a vacuum leak. do you have a cold air intake? any kind of tuner? i'd take it to the dealer and see if there are any updates needed for your computer.

 

Do a good check for some sort of vacume leak. Make sue all connections are nice and secure.