Auto Parts: 2001 jeep cherokee sport, jeep cherokee sport, mass airflow sensor

Question
My jeep keeps dieing when it is idleing or when I let the rpm go below 1. It is running rich also. we have changed fuel pump,map sensor and the injectors look good. Please can you tell me what could be wrong. I was wondering if it could be the computer.

Answer
    It could always be the computer, no matter what the symptoms.  However, it hardly ever is.  First thing I would suspect is the idle speed control.  If the rich running applies across the whole RPM range, then I would suspect the mass airflow sensor.  The MAF shouldn't affect the idle, though.  What is your basis for saying that it is running rich?  If it is the code from the computer, then it probably isn't running rich.  When the oxygen sensor fails you will get a rich-running code, even though it is not really running rich.  The best way to check for rich running is to pull a plug and look at it.  If the plug is dark, it is running rich.  If the plug is white, it is running lean.  If it's a nice light brown, like a quality suntan, then it's just right.  In spite of the computer controls on today's engines, looking at a plug is still the best way to start your diagnosis.