How much would I have to pay to replace a my 2002 ford taurus pcm?

How much would I have to pay to replace a my 2002 ford taurus pcm? - 1

Maybe $4-500 from a dealer, 100 or so from a salvage yard, eBay, etc. How do you know it is bad?

Most people replace their PCM and then realize that they wasted a lot of money when they still have the same problems.