Had a #4 cylinder misfire. I decoded computer. It gave me an PO 304 code. I Replaced ICM, Coil Packs, Spark Plugs, Plug Boots. I cleared the code , drove it for an half hour. It drove great, misfire was gone. Started it in the morning, started miss firing again .The check engine light came back on. Read the codes again. Now it says #2 cylinder miss firing. Code po302. Help I'm Drowning in code information. Throw me a life raft if you know what's going on with my car.