mammoth4runner

Hey all, new to the forum here! 3rd Gen 1998 4runner w/ ~190,000mi on it, 3.4L v6 automatic.

As I arrived home the other day my engine started running very rough and the engine/cab had a pretty hefty shake to it. It also started throwing a code. For the last two years I've gotten the P0130 code on and off, but it only ever seemed to come and go as I went up and down from altitude (I live at nearly 8,000ft), so I have ignored it.

HOWEVER, it's now throwing that code again along with the P0133 02 slow response code and my engine is going mad with an obvious misfire. It doesn't misfire all the time, just mainly on very low idle and on acceleration. At about 1k RPMS there isn't any shake or ticking - it's steady and smooth. However my idle does have some pretty solid up and down shifts.

Pulled and checked plugs/wires/coils - all are good and are meeting OEM spec and all plugs are firing. Replaced the Valve Cover Gaskets recently (post engine shake/possible misfiring problem) and cleaned the Throttle Body, U/L Plenum, and IAC while in there. Didn't mess with the MAF sensor yet.

Could all of the issues above be coming from a simple 02 sensor fail? I'm also thinking that maybe one of my injectors is clogged/malfunctioning, but I don't have any code to verify. There is no obvious vacuum leak, no cracked or unplugged hoses, it seems to just happen randomly.

Any help is appreciated!!

TommySR599

Did you ever get this figured out? I’m having the same issue and I can’t figure out what it is. I’ve replaced the front sensor and I’m still having the issue.