Misfire when cold

gocartowner

My daughter's 2003 Focus wagon, 2.0 Zetec engine misfires when cold or not driven in a few hours. It bucks violently but never stalls. After about 3 minutes, it clears up and runs great. It only has 35k on it, we replaced the plugs, wires, fuel filter and coil. Seems like it could be a warm-up sensor, I'm not sure what to try next. Any help would be appreciated...