these two codes are a code 91 and a code 96 I know that the code 91 means that the o2 sensor is reading lean but i cant figure the code 96 out my code reader book says that the secondary fuel pump circuit relay is open and my haynes repair manual says fuel pump circuit . that is all that both books say but dont tell you how to fix the problem
btw it is a 1990 lx hatch 5.0

 

96 can also mean the thermactic air system will not bypass. I would say you have an emissions related issue.

http://mustangpartstech.com/Emissions.html
http://mustangpartstech.com/EngineCodes.html