What are the steps involved in changing the freeze plugs on a 1999 Mercury Sable with a 3.0 engine?
No need to change what you call freeze plugs, (they are actually casting plugs), unless they are leaking. To replace on simply drain the radiator to below the level of the plug. Drive a chisel into the middle of the plug. Pry sideways to remove it. Clean the area throughly. Install the new plug, by inserting it and hitting it dead center with a plastic or brass hammer.