codep0305 and code 0456
 

I just returned from a memorial weekend trip and while i was away my check engine light came on. I pulled two codes p0305 5 cyclinder misfire and p0456 small evac leak, p0305 was on previously but went off for maybe two months. The pacifica might be running a little rough but i still managed a gas milage of close to 23 miles a gallon. I did add fuel injector cleaner after the check engine light came on thinking that might help. Ant ideas before i go to the dealer? The car is a 2004 Pacifica.