I have a 99 cherokee 4.0l that over the last week started getting a egg smell to the exhaust. Also when I pull up to a light sometimes the idle will drop and idle rough. I had just changed plugs,wires, air filter , oil change, and radiator flush two weeks ago and was running great. Hooked it up today and got a P0171 reading. Any ideas. Thanks for the help in advance.

 

P0171 is a lean air/fuel condition has been detected by an abnormally rich correction factor.

Runnng too lean can be caused by O2S faults, vacuum leaks from intake gasket, clogged or dirty fuel injectors, and exhaust restrictions such as a clogged catalytic converter (which may be the egg smell you're experiencing).

 

Bumped this b/c I have this exact same thing...wondering if you ever figured out exactly what it was.

 

Actually it went away. I took throttle body off and cleaned tps. Ran some chevron fuel cleaner took it up on the highway for a few miles at higher speed and went away. Hope it helps