Ford Repair: runs rough, vacuum leaks, home mechanics

Question
QUESTION: I have a 2001 f 250 superduty with the 5.4liter engine when started cold it runs good (smooth) until it warms up it seems that when the temp gets to normal range and the thermostat opens it starts missing and bucking at idle and under acceleration it gets so bad the whole truck shakes and shimmies I have replaced the fuel filter/ spark plugs / coils. any ideas would be appreciated.

ANSWER: Is the check engine light on? Can you check for codes? With an engine running this bad there should be a code in the system to lead you to an offending cylnder or problem. Check for vacuum leaks, especially the PCV system.

---------- FOLLOW-UP ----------

QUESTION: Hi Dennis, and thanks for your answer. But no the check engine light never comes on and no I haven't had any codes checked,in addition to the other things I've done I also replaced the air filter,o2 sensors,checked for vacuum leaks changed pcv valve. This condition started as an intermittent problem but is almost constant now.

Answer
Even without a CEL on, you might find codes in this one. Seems to me you need to narrow it down to one or more cylinders, which might require a coil-on-plug ignition test. Normally I would suggest looking at the coil boots as those are common areas for misfire, but you mentioned replacing all the coils. Unfortunately this is one where home mechanics are going to have a tough time pinpointing the problem. The fact that it does not act up until warm is interesting. If I think of anything else I will let you know.