OK, it pulled a P0132 code. Cmckenna, I'll be replacing the plenum with an APS kit soon, so I'll do what you suggested when I take the intake manifold off.

The story behind the oxygen sensor is this: Previous owner had to replace the cat and after doing so also replaced the oxygen sensor before the cat with a universal one and cut the harness off the pickup and hard-wired the new one in. Could this just be the wiring to this sensor? (in addition to what cmckenna said above)

Also, I just realized cmckenna narrowed my problem down to 1 thing. He's a bad a$$! Thanks CM!

 

PO132 is O2 sensor related and, what that means is that the voltage is high at the PCM which is indicative of a rich running system which is rooted around a mechanical FAULT at the IAC level.



So, again, we have a failure code but, it's not the sensor that's failing, but rather a failure in another system that is tripping this code.


Now, if you O2 sensors are M. Moused and D-Duck incorporated, I HIGHLY recommend to replace both sensors with NTKs / OEM.


Why go with a more expensive NTK sensor when you can get a Bosch / aftermarket sensor for less?


Bosch sensors are not made in Germany contrary to belief. They are made in a sweat shop down in S. America for dirt cheap and neither is the design or materials used as good in quality as compared to what the Japs have been putting out for decades. NTK is the best O2 sensor and IS OEM. I use nothing but these after trying to save a few bucks on Bosch only to have one of two flake out after 100K less miles than the NTK sensor that I replaced it with initially.


I found out the above from a component engineer friend of mine after I told him what happened with my Bosch sensor.


NTK also will last a lot longer. I think those were rated at 100K miles or somewhere around that long. I ended up getting 140K out of the OEM set. Set it and forget it. Dealer item- around 120-160 depending on which one/s you need. There's two so, replace them at the same time.


CM

 

OK, so remember the thread I started about the previous owner and breaking the exhaust manifold bolts off in the cylinder head? Well, I took the truck to a shop I trust, and had the cylinder head replaced so my headers finally dont leak anymore. While the head was off, I also had him install my APS plenum kit along with new plugs, wires, cap, and rotor. (also a magnaflow exhaust system) After all that, I noticed 2 of the O2 sensor wires were disconnected. I re-connected them and took the truck home. I have been driving it since and have not had the rough idle, or the CEL light come on. It does seem to use more gas though, only getting about 14 MPG. (but I was hauling a bed full of furniture so that might have some effects) It has been running smooth lately with no problems. I don't know if the mechanic cleaned the IAC when he took the TB off but I haven't had that sucking air sound since then either.

The only thing that has happened since then was driving 70 down the road with AC blowing, it just switched to blowing through the top (windshield defrost vents) I immediately thought vacuum line came off and was going to pull over to check under the hood. As soon as I took the cruise control off, the AC switched back to blowing to the face again and functioned normally for the next 20 minutes. Then with the cruise control set at 70 it did it again. (after 20 min of cruising 70mph) Again, when I lightly tapped the brake to disengage the cruise control, the air returned to blowing to the face again. Later when I got home from the 2 hour trip, I checked all the vacuum lines and all seemed to be attached. It hasn't done it since.

 

search for "wild vents" there is a check valve that is bad

 

I too am having this problem, although when I press the gas the engine will usually come back. I have replaced the IAC valve, plenum gasket, Intake gaskets, because when I did a vaccume check there was a major loss but still does it. I dont get the check engine light though, and the fuel pressure reads good at 15ish psi. What is actually happening is the IAC valve is opening right up and sucking massive amounts of air(thus the noise)and when this happens the vaccume guage shows massive loss, im not shure if its because of the low idle speed of the engine or an acctual vaccume leak. I have checked all the vaccume lines and cant find a leak anywhere. If anyone knows why the pcm might want to be opening the IAC valve so wide intermitently I would greatly appreciate any advice.

 

Change the 02 sensor. Mine did the same thing and this fixed it.

 

Yep it was the 02 sensors, truck runs great now, thanks EHS22, been chasing that for about a month now, quite happy, these sites and people like you are a blessing!