tahoe surging hi revs

My wifes 00 tahoe only when ac is runnin or has been runnin sometimes stays revvn hi at stop.Sh says itll tach at 1000 or 1500 with brake on.I cant ever seem to get it to happen so i really have no idea.Anyone have suggestion..

My wifes 00 tahoe only when ac is runnin or has been runnin sometimes stays revvn hi at stop.Sh says itll tach at 1000 or 1500 with brake on.I cant ever seem to get it to happen so i really have no idea.Anyone have suggestion..

the normal idle in drive is 600rpm,,,ac on or off.....
usually idle problems are vacuum leaks/PCV and hoses/ IAC dirty.....

the IAC ,,,PCV need servicing every 20-30,ooomi,,,also the vacuum hoses need checking for cracks etc...

the other issue is throttle plate carbon,,,,when cleaning the IAC this is also cleaned,,,this is common..