To note: Finally had the 4th sensor replaced under warranty last week and immediately noticed the idle dropping rather quickly on cold start now. Before the car would idle at 1200 RPM for about 2 minutes until dropping to 800 RPM. After new O2 sensors were installed, the idle dropped to 800 RPM after maybe 20 seconds! Is this a matter of the sensors heating quicker than before and therefore telling the computer to relaxe the idle? This alone is probably where the savings in gas comes in!?!?!
