Try removing the Mass Airflow Sensor (MAF); clean the two wire elements with brake cleaner, and blow dry with shop air. Give the MAF elements a good soaking with brake cleaner.
The codes you have are "Lean" codes registered by the oxygen sensor(s). The reason this happens is that contaminants burning onto the MAF elements cause the elements to be insulated, falsely registering less airflow to the engine. Thus, the engine computer (PCM) thinks it is under a light load, and thus results in less fuel being injected by the fuel injectors. Therefore, the oxygen sensors relay information back to the PCM saying "Lean". You have P0171 and P0174. Both these screaming "lean" at the same time indicates the problem is someplace upstream, feeding both banks of cylinders at the same time.
If cleaning the MAF does not work, hook up an OBD-II scanner and obtain the air flow rates calculated by the PCM. Floor the accellerator pedal for a brief moment (don't over-rev the engine) and note the maximum airflow rate. I can provide you the Cubic Feet per Minute value ranges. (But I need to know if you have a 4.6 or a 5.4 engine.) If the values recorded by your OBD-II fall outside the parameters, clean the MAF again, longer soaking in brake cleaner, and re-test. Replace the MAF if your airflow values don't match spec.
Use a good quality air cleaner element, and I suggest you going with factory Motorcraft spark plugs next time. They are worth it. Finally, don't feel bad about your failed coil. These are common unfortunate replacement parts.
Saturday, February 21st, 2009 AT 6:47 PM