Chevrolet Repair: 1998 chevy lumina 3.8L, 1998 chevy lumina, chevy lumina

Question
I have coolant in number 6 cylinder.I replaced the head and upper and lower intake gaskets. When I start the engine it will run ok for a short time but white smoke comes out the tailpipe.Then it will stop and lockup.I remove the spark plug to relieve the pressure. Not sure what else to do ?
Could the block be cracked?

Answer
If you are getting coolant in the cylinder, only three things will cause this, two of which you already replaced.  It's 9 out of 10 times the head gaskets.  It sounds to me that the head is either cracked or warped, or quite possible the block.  You will only be able to tell if you pull the head off again.  Check the deck of the block for cracks into the cylinder wall, and check the head for cracks, usually between the valves.  wish I could be more help
Jimmy