I've got a '92 pickup with a 22re. The past couple of days it's been idling really rough, to the point of almost stalling. It also bogs down when acclerating till about mid way through the rpm range(just guessing because there's no tach) then it clears up and the top end pwoer is actually pretty good. I thought it might have been the plugs, wires, rotor and cap because they were pretty bad shape but that has not solved the problem. I'm woundering now if it might be the O2 sensor? Any other thought on what it could be?
Thanks
Adam

*could be a hanging EGR valve. Should be closed until around 2500 RPMs, if its letting any gases by prior to then the ECU cant compensate for it and the result is similar to a vaccum leak. Could always check that out by temporarily blocking the pipe to the back of the intake plenum. If it runs fine and idles strong while blocked off then you have found your problem. If thats not it, then you got a whole big can of worms you get to look forward to testing and checking.
Bad O2 sensor will usually drop fuel mileage considerably.
~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

This may sound stupid but whats the intake plenum?
I'm just trouble shooting now.
Thanks

The plenum is the upper portion of the intake manifold that says EFI on it. In the front your air tube connects to the throttlebody which is bolted to the plenum, on the back side is where the EGR bolts to it with (2) 12mm bolts.
~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

how long before O2 sensors usually go bad? and what could cause them to go bad prematurely?

ok thanks. looks like it might be time for a new O2 sensor.