P0171 on an escort is typically a vacuum leak. Most common spot would be a vacuum elbow right at the PCV valve. The PCV valve has a plastic tube that runs underneath the ignition coil to the bottom of the intake manifold. Check both ends of this tube for a soft rubber elbow...they are very common for cracking and creating a vacuum leak which sets the code P0171...If you find a leak you can clear the code by disconnecting the battery for a couple minutes, but make sure you repair the leak first...can be other issues but this is by far the most common...
