95 4WD 3.0 XE, This problem started two weeks ago while plowing. Often when plowing a final push the rpms are low to the point where there is even an occasional stall. The check engine light then lit up, and at low rpm, even when starting out going through the gears, I couldn't rev the engine high enough to get out of that funk. The first couple times I'd crank it out on the open road for a bit, the light went out and everything seemed to clear up. This last storm however, it started doing it more often. Now, I don't even have to be in 4WD and if I'm below 2500 rpms, its bogging down on me (over 2500 is clears up). It happens about 50% percent of the time (the other 50% of the time it seems to run fine.) Checked the trouble code - O2 sensor. I have had other vehicles where the O2 sensor code was thrown,but it didn't seem to affect how the vehicle performed. There is clearly a problem here though. I read all the previous posts about cleaning (carefully) the MAF, checking plugs wires,etc. Question to you guys is will a bad O2 sensor cause the problem I'm having, or is the problem I'm having causing the O2 sensor to throw out the check engine light?