I had this problem many years ago with a set of MSD plug wires. I swear the boots had literally bonded themselves to the plugs. No matter what I tried, they would not come off. I tried the grease also, no luck. I would twist and pull so hard that a couple of the boots literally ripped in half. Most of the time the boot would stretch so far that it pulled the wire out of the socket. After fighting them repeatedly, I junked them and went with Firewire spark plug wires and never had a problem. I've also used others, but have never gone back to MSD wires.