2004 Ford F 150 Hi Sir Had Check Engine Light Read Codes Giving Misfire Cylinder

Hi Sir

I had the check engine light when i read the codes its giving misfire in cylinder 3 and cylinder 8 , i had change the spark plugs and clean the injectors and the same problem still there misfire in cylinder 3 and 8 what i have to do after i changed the spark and clean the injectors and the coil i had change it all before 5 months, can any one help me in that