2011 E90 328i going through ignition coils
 

My dad has been having issues with his 2011 328xi going through ignition coils constantly. He said he replaces one or two a month. He had the valve cover gasket and PCV system replaced and that fixed it for about 3 months but the problem has returned, misfiring, stuttering, etc. Does anybody have any advice on the issue? Is this a common issue with the N52 engine?