too rich both banks

I have a check engine light on a 1997 Tbird 4.6 which I am having difficulty resolving. I have been on a Tbird site for a while but I am getting some confusing suggestions, so I thought I would check out the Mustang experts. The 97 Bird 4.6 has 201,xxx miles. DTC codes P0172 and P0175 "rich both...