Have a 1997 caprice idles up and down. Changed idle air control valve
Car still idles up and down, while sitting in park or in drive.

Help don't know where to start now !!

 

Hi,

maybe there is a vacuum leak?

 

i have a 93 that does the same thing. the only difference is mine only does it when i first start it up. also. i would love to see a pic of your 97 caprice.
i heard of them but i always thought it was a typo..

 

Had the same problem and just replaced oxygen sensor today,all is great now.

 

i had the same problem with my 91 caprice and had changed egr valve,map sensor,plugs,wires and cap,still did it.Checked fuel pressure,pressure was low.changed fuel pump and now runs great.Fuel pump is in the tank so i cut an access hole in the trunk and replaced it that way instead of dropping the tank.took about 20 minutes.

 

having same issue on my 97 K1500, unplug your Knock sensor if it settles down you have noise in the motor causing the ECM to act stupid to compensate for what It thinks is ignition Knock. I tightened up my rocker arms and it settled down a bunch, P.S DO NOT DRIVE IT WITH OUT THE KNOCK SENSOR PLUGGED IN!!!! YOU'LL RUN THE RISK OF BLOWING THE MOTOR