which type of ignition coil is in position 4

if that's what you need is an ignition coil,depends if round or square coil? 8 per car. AC DELCO *Square* Part Number: D581 or AC DELCO *Round* Part Number: D585. never seen a code say replace a part,but it is possible that's what you need?

Swap coils with another cylinder to see if misfire follows that coil. There are more possibilities than the ignition coil for a misfiring cylinder than!