It's either going to be an injector, plug/coil, or compression issue. Check the plug for damage. You can also change the #7 coil with another easy to reach coil. Say swap #7 with #1. Clear the codes and drive it around till the light comes on. Get the code scanned and if the code is now p0301(misfire #1), it's a COP. I know they say check the boots, but I work for a dealer. Just replace the whole coil. We've had to many that we've just replaced the boot(like ford says) and they came back misfiring shortly after. If the misfire stays, it's problably an injector(could still be compression issue though). Whatever you do, go Motorcraft parts(not aftermarket).....