ok, i unplugged the pre-cat o2 sensor. idle is back to normal and it runs smooth. i guess that's the problem.

 

consider yourself lucky. my truck eats money in larger bites, usually hundreds of dollars at a time,

 

Are you supposed to actually remove the pre-cat 02 sensor from the converter or simply disconnect the wired connection ,or both?

 

I'm not sure. I've read both. I was going to try it both ways, honestly. When i disconnected the sensor, my idle went back to normal.

I still have to check the plenum, but that didn't seem to be the issue. Granted, that could still be what killed the O2 sensor.

 

You unplug the o2, move the wire/connector out of harms way, and pull the o2 from the pipe/cat. Then test drive. But in his case, the problem was noticeable at idle.

 

So does mine brother. First it was a coolant leak, then timing chain, then hub studs, then transmission, then TWO transfercases and driveshafts.... the only nice thing ive done to the truck otherwise are spark plugs and an oil change. And new valve cover gaskets. (Sorry for being offtopic)

 

Disconnecting the sensor tests to see if the sensor is bad. (which in your case, I do believe is indeed the problem.) Removing the sensor from the cat, tests to see if the cat is getting clogged. (if it runs better with the sensor removed, that indicates the cat is on its way out.)

Do both, see what happens.

 

Also check your crankcase breather/filter. If that is clogged it can cause a few idle problems.

 

i disconnected that o2 sensor and drove it to work today. it probably drove better than it has in the past 2 years i've owned it.

I'm going to order a new o2 sensor. maybe my gas mileage won't suck (as bad) now.

 

Be sure to get it from RockAuto. It is about half the price as you would get it at a local auto parts store.