Hi, you mentioned oil around the threads of a spark plug. Since you have changed the plugs with new ones, go back out and removed the one that was oily. Is it still oily? If so you will be experiencing lower compression in that cylander hence the rough vibration.
Do not for any reason try to adjust your timing unless you have the proper tools and instructions on how to do it. Your on-board computer monitors and manages the timing of your engine.
Saturday, August 12th, 2006 AT 8:56 PM