 1999 Escort ZX2 code P0171
2.0 SOHC - So my girlfriends car just started having idleing problems... it was slightly rough but didnt affect driving at first. After a week or two it then started affecting driving (loss of power, Horribly rough idleing when coming to a stop, and has once or twice died) Somewhere in this she told me the check engine light came on and came up with the code P0171. O2 Sensor detects that engine is running lean on fuel. My first Inclination was that the MAF was dirty or went bad... i cleaned the MAF which only fixed the problem for a couple miles. I think just resetting the battery caused it to run smooth for as long. Has anyone had this code and what was the most likely cause. I'm really close to replacing the MAF which i think is the cause but it would cost $105 and if its not the problem i will lose my money. | 
