2000 ES300 misfire
 

Got a PO306 code.
Checked for spark and found none at the plug.
Flip-flopped 2 coils and came to the conclusion that the #6 coil was bad.
Bought new coil from dealership and replaced the wet plug.
Same problem.
The spark plugs were replace a month ago, but regular resistor NGK plugs were used instead of the iridiums.
Could this be the problem?