1998 Chevy Suburban engine runing too rich

Hi Herbert Dyer and TY for the donation and we wish you a Merry Christmas and Happy New Year 2010.

Running rich is a fuel mixture that is too much fuel than air that can be caused by the following below

A bad O2 sensor, excessive fuel pressure (bad fuel pressure regulator or plugged return line), leaky fuel injectors, dirty air filter or restricted air inlet, or a defective coolant sensor that prevents the engine management system from going into closed loop mode.