Just wondering what your engines are idling at? Mine idles at 500 seems a little low and it has a stummble at idle.
Have replaced the following:
Injectors
Plugs/wires/cap/rotor
O2's
Cat
Muffler
Pcv
Vacuum lines
All recently just to get it to pass a smog test and still almost failed on hc's
Any help would be great thanks,

 

My old 2000 Bravada would idle ~500RPM once warm, in gear.

 

GM has perfected the low idle, my blazer idles at 500 in gear and 650 in neutral. our 2007 2500 does the same thign its normal

 

If the idle is steady, both in Drive and park, and seems controlled while warming up, then it's normal.
The PCM knows what it's doing. Test for that is to turn wheel while sitting at a stop. If it stays at '500' - or whatever- it's meant to be.
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For general info purposes:
DO NOT adjust throttle stop screw {providing there is one} to increase idle. If there's a need to increase idle while working on something, shim it. Like a piece of cardboard, whatever.

 

thanks, good to know!