02, Evap, and Misfire error code question

[NikkiGA]

Hey guys. New here and had a quick question. I'm familiar with cars, but not so familiar with 4runners and their quirks. I just got my codes pulled at Autozone and I got the following ones:

P0303 - Cylinder 3 misfire
P0440 - Evap system small leak/ no airflow
P0133 - Heated oxygen sensor, bank 1 Sensor 1 circuit slow response (O2 sensor)
P0130 - Heated oxygen sensor, bank 1 sensor 1 circuit malfunction (same O2 sensor)

The engine is definitely misfiring pretty badly, to the point where I thought my transmission was slipping. I should also note that I ran without a gas cap for a few weeks about a month ago so I'm hoping P0440 is related to that.

My question is, do you think the O2 sensor errors could be causing all of this? I'd really prefer not to hunt down a vacuum leak or have to replace the EVAP system. Is it possible the code for the evap system is left over from the missing gas cap? The check engine light was on until I put in a new one and then it went away. I'm just wondering if the computer didn't store that error from before. I know the O2 can cause misfires so I'm fairly confident those two are related.

Thanks!

Oh, almost forgot, 1997 3.4 V6 Automatic.

 

[kball]

Sounds like you need a little tune up. Plugs and wires will hopefully clear up the misfire on 3. A new pre cat O2 sensor will fix up your 130's codes. A missing gas cap is definitely a problem. Once you get the new O2 sensor in I would clear the codes and see if any come back.

 

[NikkiGA]

I was thinking of doing plugs and wires while in there. Thanks! I'm taking it in tomorrow to get checked out so I'll let you know what happens. I'm just glad it wasn't my transmission!

 

[NikkiGA]

Brief update of success:

Replaced:
Plugs
Wires
O2 Sensor
Transmission Flush
Oil Change

She runs like a top! Thanks for your help, kball.