idle way to high

[1bad5.0]

its a 94 GT i have run test on this it pops that the MAF sensor is running max voltage and then it says that the voltage is to low ihave change my IAC and it does change a thing. what it does is when i start it the rpm jumps to about 1800 then as i drive it the rpm increases to 2500. Ihave trouble shooted and when disconnect the air intake pipe off the throttle body the idle jumps down. I also plug the hole on the throttle body where its sux air in to the IAC and it also jump down it seems that to much is flowing threw that hole or something. it is also running lean because when idles at that speed for like 10 mins the headers turn glowing red from the heat out put and the test also said that it was running lean

 

[1BAD89GT]

its a 94 GT i have run test on this it pops that the MAF sensor is running max voltage and then it says that the voltage is to low ihave change my IAC and it does change a thing. what it does is when i start it the rpm jumps to about 1800 then as i drive it the rpm increases to 2500. Ihave trouble shooted and when disconnect the air intake pipe off the throttle body the idle jumps down. I also plug the hole on the throttle body where its sux air in to the IAC and it also jump down it seems that to much is flowing threw that hole or something. it is also running lean because when idles at that speed for like 10 mins the headers turn glowing red from the heat out put and the test also said that it was running lean

Well it could be a few diffrent things....could be the IAC since it idles down when you unplug it,Check your Air filter could be Dirty and clogged,Also check the inside of your MAF sensor make sure no large pieces of debree are hung up on the screen or blocking air from flowing past the sensor,Check your timing.check your throttle body make sure its not sticking.if your for sure your running lean could possibly 02 sensors....Have someone check the codes if nothing seems to work.

 

[Idwitheld-1`]

If starting cold (below 180F) it's not O2's.
Look for unpluged vacuum lines. Especially the PCV line. If it pops out of the grommet it will jump your idle by at least 500 rpm's. Listen for sucking sounds on vacuum lines. I found this once on a GT....rotted hose on the charcoal canister. If you have unmetered air you probably will have a lean condition...the o2's will try to compensate.