ok, so my car starts to run ****ty so i take it and put it on the scanner, no trouble codes pop up, but when i looked at the o2 sensors, there going from 800 down to 150 and vica versa, so there just going crazy, are they bad? need replacement?

 

No, appears to be normal. What's the fuel trims doing?

 

To understand why that's normal for the O2 sensors in closed loop, read the "air/fuel managent" part of this. Might also help you with other scan data:

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

well, it's running really rich and running like *** too....so that's why i thought it could be o2 sensors....what is the fuel trim? oh yeah, my fuel mileage has went down to about 10 miles to the gal.

 

Read the writeup I linked. The fuel trim is the learned long term fuel correction or "BLM" (block learn multiplier). You can retrieve the BLM's for the 18 operating cells (a function of RPM and MAP) to determine if the PCM is having to add or subtract fuel. Elevated BLM's can often be the result of a "false" lean, due to exhaust leaks before the O2 sensors or misfires. A false lean will cause the engine to run rich.