1991 5.0 fault codes. 3-2 and 4-3

I had check engine soon light come on. I checked codes and 3-2 and 4-3 came on. can anyone help me on this? and how can I correct these codes?I checked on a newer model and it came up exauste gas reciculation system and knock sensor (ks) circuit wich was on a 96 modle.If they are the same how can I check and repair them? Thanks for the help because I need to get it running yesterday............