Poppy- Just as likely, the rubber boot on the coil is bad. Try swapping just the boots instead of the coils, boots are a helluva lot cheaper to replace. Many, many a good coil has been changed because the $3 rubber boot was bad...Yesterday my daughter made a quick run to the grocery store to pick up a few last minute items. She took my car because the check engine light came on in her's.
While the bird was baking, I got out my scanner, and pulled codes. P302, misfire cylinder number 2. I popped the hood and found that she has COPs coil on plug ignition. One ignition coil for each of her four cylinders.
Misfire could be caused by faulty fuel injector, bad spark plug, or most likely a faulty coil. So I pulled and swapped the coils for cyl, 2 and 3. If the misfire moves to cyl three, I'll know that she has a bad coil. They are extremely easy to swap. So I guess today, we'll find out.