First, welcome to the forum. This is the forum to introduce yourself - we have technical forums to help you with problems - but this one ain't it.

Ok, none of the REAL engine guys have responded, so I guess I'll try.
So, you are essentially telling us that the computer thinks the car is running too rich...

Have you EVER had ANY codes or indications that one or more O2 sensors were flaky?
How many miles on the car?
How old is the battery (PLEASE don't tell me it 'checks fine', I'm sure it does, but I didn't ask that! These cars, and many cars, are really touchy about clean electrical power.)
When were the air filters last changed?
You might also take a GOOD LOOK at all the vacuum lines around the throttle body.
Something tells me to mention fuel pressure - it's not all THAT hard to measure the pressure in the rail, might think about that.

Above all, does the car run fine - is this just a code that you want resolved? Or is the car still not running right?
Answers to all of these questions can help get us to where you want to go!