[cadillac512]

We remove stuck plugs in engine parts every day at work. Use an oxy/acetylene torch to heat the plug only(not the manifold) to a dull red. Have an air blow gun ready,turn off the torch and immediately blow air into the center of the plug to quickly cool it. Keep blowing until it cools down enough to work with it, and spray some penetrant on the threads. If it smokes it's too hot. The rapid cooling shrinks the plug, breaks the bond and they usually come right out with very little pressure.