Possible o2 sensor or something else?

[v8killerr1]

The car has been throwing the p0300 cel which is random engine mifire and has been bogging down big time and hard to accelerate with a bad idle. It will drive fine for about ten or so miles then start doing this. The air/fuel meter is stuck on lean at any rpm and will not cycle like normal. The spark plugs have been gapped at .028 and it has new wires. The 02 sensor is a bosch sensor that was replaced about 3 years ago. Does anyone else have any thoughts. Thanks

 

[GSntncT]

3 years ago....hmm, indeed a possibility. Replacing the 02 would be the first thing I'd do. Just in case you do, I just want to say that you shouldn't rely on your A/F-unless it's wideband. From my experiences, I've killed many an 02 due to running excessively rich. How long ago were your plugs replaced? I'd check them too.

 

[roadrunner2176]

Try an clean your sensor first with some carb cleaner and a tooth brush if that is what you believe is bad. It can be done without killing your sensor. Spray down the tip with carb cleaner, put some cleaner in a the cap of a spray paint ca, or something similiar and let the tim of the sensor sit in it for about 10 mintues. Use the toothbrush if you think you need to, otherwise spray some more carb cleaner on the tip, shoot between the holes, and let it sit until it dries, maybe 10 more minutes, and put it back in.

Otherwise, I'd check wires, plugs, and coil.