It seems like my 2004 6.0L excursion take sforever to warm up. Unles it idles for 10 minutes it is sluggish. i would have thought this was just a diesel issue, but I valet several days a week and drive plenty of PSD 6.0L trucks that are never sluggish after sitting for several hours. I recently replaced my fuel filter. My air filter could probably use replacing, but i don't understand how either of these would change after the truck is warmed up. Thanks for any suggestions.