[99Classillac]

Where is Ch Ch? I took the airbox out today and took the IAC valve out today. I took throttle body cleaner and sprayed into the IAC hole and opened the butterfly and cleaned all in there. I put it all back together and it was running perfect all day! Then I go home and it starts to idle high again. It's not even idling till it shuts off, just really high. I shut it off and waited 5 minutes, then cut her on again and she is idling right again. I decided to unplug the IAC Valve and see how it runs without it plugged in. I wanna see if the IAC valve is at fault. I figured unplugging it while it is idling right will make the vavle stick in the correct position. Without any input, it won't move from its current setting. Also, I used to throw 2 codes, P0171 and P0174, both banks being lean. I cleared codes, now only bank 2 is running lean, P0174. Anyone think the O2 sensors might be bad? I was thinkin the bank 2 O2 sensor might be giving false readings, then again I would throw a bad O2 sensor code right? I looked at plenum, but it looks ok and I don't hear a vacuum sound coming outta there. I do hear a slight INITIAL hiss when I throttle the engine by hand under the hood. But the hiss is initial and then goes away. I think that is normal though. Anyone have any helpful input?