My Tahoe has been idling rough for a few weeks now, getting frustrated. It still starts really easily and runs great under load but at idle it shutters and idles erraticly. Three trouble codes came up - 0171 (system too lean - bank 1), 0131 (O2 sensor circuit low voltage - bank 1 - sensor 1) 300 (random/multiple cylinder misfire detected). I have checked the vacuum system and it is good. All the injectors sound like thier working, used a stethascope to check. I did change the battery recently, not sure if that matters. plugs were replaced not long ago, I pulled one any way and it looked ok. The fuel regulator is clean and dry, so I dont think thats a problem. Would a weak fuel pump cause this? Would a bad tank of fuel cause this? I just fuelled up at a different station and added injector cleaner to the tank. I'm not sure if this matters but my Tahoe is a flex fuel although since i've owned it we have only run gas in it. Any thoughts or advice would be greatly appreciated.

 

It turns out that replacing the intake gasket got rid of the rough idle in my Tahoe. I would suggest to any one else who has this issue to try this fix as one of the first. The gaskets are cheap compared to some of the other parts, ya its a little more work but it still only took me, and i'm not a mechanic, about 2.5 hrs. I hope this helps someone else.