you have to do some trouble shooting to determine the specific issue first.
as previously stated by "Jetdoc", and myself,
http://answers.yahoo.com/question/in...7070014AA2zc8n
EDIT,
i will add, you are going the right direction as this *generally* does not warrant an engine replacement....... but anything more than a head/valve issue will *likely* cost more than it's worth. barring head replacement.
as replied in your other Q,
if you put a bit of oil in the cyl in Q, do a compression test, and the compression raises, it's likely a ring job. and likely you'll find other issues if you perform proper inspection procedures on related components when performing that repair. that would make me reconsider buying it all together.