I have 97 150 it has a misfire on cylinder 4 and 6. I put new coil packs on and new plug wires. spark plugs are only a year old I have know idea what else it could be

 

Codes please only because it insures we are addressing the correct cylinders.
Why have you not looked at the plugs since they are part of the operation?
Never assume they are good.
Cylinder health is a possibility.
Good luck.