I have a 2001 ZR2 2.0, auto. I'm having problems with it wanting to die when you pull up to a light. It runs good as long as your going, I took it to a auto store, they hooked there machine up to it, and said it was running rich, then I took it to an actual garage and they hooked it up and said there were no faults, but it will spit and sputter when it is at idle,
Any clue on what it is?

do you have a check engine light on? It might be a bad o2 sensor, or it could be air temp sensor. egr valve, or egr valve sensor. Just to name a few.