Ive tried everything to get my '04 F150 5.4 to idle smoother , finally saw a brand new sealed in the box throttle body with all sensors on Ebay from a Ford dealer in NC , for $199 , I got it last week , changed it out in 15 minutes , runs smoother than it ever has since I got it with 44,000 miles on it . for that kind of money , why would you even mess with it .
PS it has 156,000 on it

 

My brother just picked up a 04 half ton with 275 thous kms (5.4 3V)

His idles rough to, like around 800rpm. There is a CEL we havnt gotten a scanner on it yet though to see what codes its throwing.

We cleaned the throttle body with throttle body cleaner today noticed the butterfly valve didn't want to sit completely closed almost like theres a stretched spring in there? Also cleaned the maf with maf cleaner, still idles hella rough

But that being said plugs havent ever been done so i am thinking that why there's a rough idle

 

The engine couldn't run at all with a completely closed throttle plate, so why would you want to see it closed?