You should have 3 digit codes (ie a 332 or 337 etc). A 3XX code is EGR related, so at least that is narrowed down. As wavinwayne pointed out, there can be more than one cause for EGR codes, keep an eye on it.
The 176 (and 172)is often caused by a MAF problem, as well as any vac leak. No two O2 sensors are alike and as soon as the entire system goes lean due to a MAF/vac leak/fuel pressure concerns, the weaker of the O2 sensors will code. Not unusual to see someone slam in a new O2 sensor on one bank and have the car come back a week later coding the other bank lean. Examine the MAF, look for any "fuzzies" on the hot wire, clean with elec contact cleaner (not brake clean) and check all vac lines, and in the case of the SOHC V6, the intake gaskets. In this situation, eventhough you have an O2 code, the O2 is likely the last component in the chain to cause the problem.
The 176 (and 172)is often caused by a MAF problem, as well as any vac leak. No two O2 sensors are alike and as soon as the entire system goes lean due to a MAF/vac leak/fuel pressure concerns, the weaker of the O2 sensors will code. Not unusual to see someone slam in a new O2 sensor on one bank and have the car come back a week later coding the other bank lean. Examine the MAF, look for any "fuzzies" on the hot wire, clean with elec contact cleaner (not brake clean) and check all vac lines, and in the case of the SOHC V6, the intake gaskets. In this situation, eventhough you have an O2 code, the O2 is likely the last component in the chain to cause the problem.
