What would cause error code P0304. and how to fix it on 2005 Scion xB

Recently had oil change, and follow schedule. Driving the other night car smelled hot, just made it home

Asked by for the 2005 Scion xB
304 means misfire 4 th cylinder usually after 100,000-120000 miles the coil packs will go bad and are usually the cause of this