My 2.0L Jetta had an intermittent misfire, only at idle. I took it in to the shop, and they fixed a vacuum leak and replaced the plugs. The car drove home fine, but the next morning it was misfiring at all speeds. When it got back to the shop, they said that the coil pack was bad, and it would cost another $240 to fix. I couldn't help but wonder if they might have done something to cause the pack to fail, since it seemed to be working fine before I took it in. Their explanation was that the coil had become accustomed to sparking at an adjusted (more powerful) setting to account for the vacuum leak, and when it tried to go back to the factory setting, it quit working. Also, all of the stress from running at a higher output wore it out. Most of that sounded pretty booooogggguuuss to me. Do you agree?