My Escape has been idoling rough lately.. I got codes 171 and 174? I believe those are the two as I don't have the code reader in front of me.. Those codes would be "System to lean (bank a) and System too lean (Bank b)". I have replaced the IAC to no avail.. Then tried replacing upper intake gaskets and changed all the pulgs while I was in there.. Still had a rough idol.. So I figured to try a new air filter, and that also did not help. I am now getting codes 400 and 404? As I said, I do not have the reader in front of me.. Those are Misfire in cylinder 6 codes.. Any relation between the two (Rough idol and misfire)? I guess a coil pack could cause the misfire, or a bad spark plug. I'm lost on the rough idol though.. It's getting too much air in the system somrwhere. Perhaps the lower intake gaskets? Any help would be appreciated.