Code P0304 and P0130 (Loss of Power+Rough Idling)

[Andrew4Bama]

I have a '97 4WD Limited, and and about a week and a half ago, it all of a sudden started getting shaky every now and then when I would give it a little gas. Then when I would come to a complete stop, it would start shaking like crazy and the exhaust was sort of pulsing (white exhaust sometimes). Shortly after that, the check engine light came on, and I took it to Advanced Auto Parts so they could check the codes for me. P0304 (cylinder 4 misfire) and P0130 (o2 sensor circuit bank 1 sensor 1) both showed up. The guy said that the P0130 was probably causing the P0304.

I haven't done anything to it since then in terms of trying to get it fixed, but it's still doing all of those things I mentioned, and the check engine light is still on. Also, my mpg has is terrible right now. So my question is, would it be safe to assume it's the o2 sensor, and go ahead and replace it, or is it just as likely that it could be something else?

If so, is this the one I should get to replace it?: Oxygen Sensor | AutoZone.com

Thanks!

 

[Acidmeld]

Sounds to me like a bad head gasket blowing coolant into the exhaust. Try to run a compression test. An o2 sensor would cause the entire bank to misfire not just one cylinder.

 

[Andrew4Bama]

I think you might be right. I just checked the coolant, and there's almost none left. The only thing is though, it hasn't overheated yet. Is there anything I can do myself to know for sure if it's a bad head gasket?

 

[Andrew4Bama]

Update: I finally just gave in and took it to a relative's shop about an hour ago. He checked it out as soon as I dropped it off and he just called saying that it was simply a bad spark plug wire.