2001 max with 205,000 miles. I've been getting the p1320 code only and no other 300 series code to pinpoint the exact coil. I am going to replace my spark plugs with (NGK). I am thinking of starting off replacing the #1 and #6 coils. Is this a waste of $ or maybe taking them off one at a time engine running to pinpoint coil?? I am using either Hitachi or OEM coils.

 

If your coils are going replace them all. Eat the 5-$600 and be done with the issue. I chased that issue for a year back in the day.