replaced the #4 plug and no change in behavior. Still idles crappy and vibrates until 2k before smoothing out. Also can hear pinging/ticking occuring on the passanger side, so cylinders 1-4. Could a spark plug blowing up like that damage the coil? I don't want to drop $50 on a coil to find out it isn't the culprit. Any suggestions? A code reader would definently come in handy right about now.