My CEL has been coming on for some time now. I've done a number of tune-up type things along with some of the other fixes posted here. I've done the TB cleanout, new plugs and wires, a new MAF sensor, a new EGR valve, a new IAC motor and a new fuel filter. The O2 sensors have approximately 10 to 15k on them. I keep having the “fast to slow” idle problem with cooler weather. I just checked for a fault code and I believe the readout is 176. Which though the Hayes manual says "Oxygen sensor- Mixture too weak". I'm not sure were to go from here. The dealer has been of little help (except to lighten my wallet). Any suggestions would be helpful.