During the past week my check engine light has started to blink off and on. My gas mileage has dropped considerably, when i'm sitting at a light my rpm's go up and down and my 4runner is really sluggish.

I have a 1997 4runner SR5 V6 2wd auto with 161,000 miles

 

I had the same thing happen to me a while ago on my 99 taco. I had about 152k on it. I had diagnostics run and it was either that or the catalytic converter. Pretty sure to tell they had to further test with some voltage readings? I didn't want to waste my money on tests, so I drove it for a while. Started getting some rattling and it in my cat. Started spitting out honeycomb through my tailpipe. Replaced it and check engine has been gone. I have yet to replace an O2 sensor, but they say around every 100k.

I didn't have the surges that you seem to have, so that to me would indicate a sensor on the way out; my buddy told me (correct me if I'm wrong) when a sensor is out or going out, the on board electronics constantly try to adjust themselves (and the engine) to compensate for the dead sensor..

 

as far as the jumping up and down, does it do it when you have the break pressed?

that happened to me and i adjusted my idle and it stopped, might try that.


or your timing could be off

 

I just had that problem replaced the idle control valve runs great now... Mine would idle up to about 3000 rpms when I turned it on and would go up and down... not to jack the thread but when you turn your truck on about how many rpms should you be idling at???

 

blinking means misfire


all other codes would stay on for at least 15 minutes