Just clean them up with Brake Cleaner and stick 'em back in. If they aren't giving you problems now, they should be good to go. They are easy to change later if a problem pops up. They are just too expensive to replace if they don't need it. I actually had a coil that was missing due to oil in the well. After sealing the valve cover and cleaning the coil, plug, and boot, I stuck the missing coil back in and it's worked perfectly ever since. If the car is missing because the coil is grounding through the oil, removing that ground should cure your problem. Try it before you throw away good money. Replacing coils is NOT hard!