2001 F-350 had this problem for one day at 36,500 mi, (just out of warranty), engine sputters and feels like one or two cyls misfiring when warm and at low rpm (less than 1800 or so), let the truck sit overnight and the problem went away. Now at 39,000 the problem is back. Runs fine when cold, but when warm and at low rpm under load (accelerating or climbing slight grade), still have same rough idle & low rpm condition, runs better at 2000+...

Changed iacv today but still runs rough when warm...

Any suggestions????

 

Welcome to the forum

Could be a coil or plug.
try cleaning the mass-air sensor too.