I'm doing a plug and wire change on an 04 Santa Fe 3.5L. I bought it used with 75,000 miles, the previous owner said he done the plug change (I'm skeptical based on what I'm seeing) . Now at 145,000 miles and running rough, I'm committed to doing the task. The front 3 plugs w/coil overs went smoothly. After removing everything necessary to get to the rear plugs. I can't get any of the boots to come off. I have twisted them both directions, pulled and cussed at them, they aren't coming off. I decided to do the experimenting on #5 plug. I tied a string under the top seal and pulled up and it tore apart from the hard plastic tube, I broke that up and now I can't get the bottom rubber part off. Any chemical that will melt this? Any ideas or tool to remove the other two boots in the whole?