vintageman

If you have a misfire on a certain cylinder, try swapping a COP from another cylinder to the misfire cylinder and put the suspect one on the other cylinder and then next time you get the misfire, check the code, if the misfire moved to the different cylinder you found your issue. If the misfire stayed at the same one, look at the plug or the fuel injector. Make sure that you check the electrical plug at the COP and the injector as well to make sure its plugged in correctly. Keep troubleshooting, I don't think its worth selling just yet.

Tom