1997 Dodge Neon DEL indicating lean air/fuel

UPDATE: I have replaced the MAP sensor hoping that was the problem. However I drove it tonight about 30 miles and the CEL came on again. I havent had a chance to check the OBDII code yet but I suspect it will be a P0171 Lean Air/Fuel ratio again.
I think I may have to go over the vaccum lines and the intake again looking for leaks. I havent checked the exhaust system for leaks yet and I think it may give the 02 sensors a lean reading if there is a leak there, correct? Any input you have would be greatly appreciated. Thank You

Update: OK I have found and repaired the problem. There seems to be an issue with the wiring harness for 1st gen neons. The harness routes around the drivers side of the valve cover and leads to the knock sensor, upper o2 sensor, alternator, and lower o2 sensor. Where it goes undr the exhaust manifold after the upper o2 sensor it rests on the frame and the metal rubbes through the wiring grounding out the wires. I just took out the intake snorkle and the air box and unhooked the sensors, pulled the harness up so I could rewrap the wires. I then put some heat shield around the wires and reinstalled it. The car has never ran better and no CEL to date. WEEEE!