Idle Problem....
 

Ok....I start my car...it's runs for a few seconds, the check engine light comes on and then the idle goes from 900-1800...and just keeps going up and down....any ideas?

Bad IAC valve?

What is the code?

edit: btw IAC will not throw a code on tpi.

Zero, get us the code from the ecm, and we'll go from there...

...yes that sounds confusing but here a quick explination. you need to find the ALDL(assembly line diagnostic link" it will look like shown in the pic, on your car, it'll be in the area of your right knee when driving...

http://www.chevythunder.com/aldl_terminal_location.jpg

ok once you found it, take a small piece of wire, like 2" or so and strip both ends to make a "jumper".

NOW, make sure the car is off, then insert the jumper wire into terminals B & A on the ALDL connector(the two on the top right as shown in this pic)

http://www.chevythunder.com/aldl_terminal_id.jpg

Once you have the wire in place, grab a piece of paper and a pencil, then turn the key to on, DO NOT CRANK IT, just so everything powers up.

Keep your eye on the SES/check engine light. It will start to flash in a pattern. if the diagnostic system is working properly, itll flash the first code like this.... flash-pause-flash-flash...thats will repeat 3 times(every code will eb repeated 3 times), and that code is "12" since the first sequence of flashes is the first number, then a pause then the second set, so for example, code 51 would be, flash-flash-flash-flash-flash-pause-flash. And like i said every code will repeat 3 times. The codes will also be shown in numerical order from low to high. Once all codes are done, it will flash code 12 again and continune flashign it. When you egt there, turn off the car, and REMOVE the jumper wire. make sure you dont leave it in there.

Once you have the code(s) from you ecm, post back and i'll give you a list of what they are and what to do next.