What if we have changed coil,checked spark plugs, but still the PO300 code is reading?

Question

Code PO300 is still reading in my buick lesaber.We have changed spark plugs, check coils but it's randomly misfiring and the misfire is two cylinders?

Answer 1

What is the misfire at the 2 cylinder? if its right next to each other this can be head gasket , if the misfire is the  ignition companion cylinder not only the coil can be bad but the ICM (ignition control module)