i have a 94 3.4 camaro and i been having this idle problem for a few months now... on a cold start it idles fine.. when it warms up tho the idle jumps up to about 1800 rpms and check engine light comes on (when im in park) as soon as i put it in drive it goes back to normal idle and check engine light goes off? i can drive around all day and the light wont come on intill i put it back in park. i got the car hooked up to a computer and it said change IAC valve.. so i changed it that day also cleaned tb and changed the pcv valve...... but nothing had changed still same idle problem and my gas milage sucks ever sence this problem
please help

 

Sounds like there might be a vacuum leak? Do you hear a hissing under the hood anywhere? Other then that I'm not sure, but these guys on here will be able to help you out.

 

try cleaning the egr valve. test your evap system.

 

The park/drive situation has me baffled but definitely check the vacuum hoses on top of the upper intake manifold. There are a couple of specially formed ones that crack/split and that will cause big problems.

 

i do not hear any hissing under the hood.. im goin to try cleaning the egr valve and check for any cracked hoses sometime this week hopefully it gets a little warmer =(.. how do i do i evap test craby?

 

found in the how to and faq sticky at the top of the 4th gen section https://camaroforums.com/forum/lt1-l...-system-51219/

 

thanks man im going to check that out asap ill let you guys no how everything goes thanks for the help everyone!!

 

it said replace IAC and not TPS? try resetting it if evap is not the case.

 

did you reset the new iac. number 47 on the list here 4th Gen LT1 F-Body Tech Aids

 

no it didnt say TPS.. but as for resetting the iac valve i had no idea i had to do that auto zone told me to just push the pin in intill it matches the lenth or your old one and after 100 miles it should idle normal?