I too have had electrical trouble with my 03 Chevy silverado such as window switch, gauge cluster and other typical malfunctions common to that year. So just from mechanic to mechanic I would start with the following, although your symptoms are that of a faulty alternator. First and foremost test the alternator and battery, while the engine is running the alternator should be putting out 14v to charge your battery while running your acessories. Any voltage below could possibly cause this stall. Now if everything checks out I would start cleaning sensors such as MAF, TBS so on and so forth as well battery terminals. Also you might check out your terminals and make sure you dont have a wrong polorized metal on the wrong wire. The do make terminals specfically for positive and negative wires. Then I would start checking main connections. GM also makes a thermal paste that corrects the uneven surface contacts on the inside of sensors. Its that white stuff you see after you disconnect them. If all else fails you could just bring it out to me I am sure I could find your problem. Truth is there are many things that could cause this, but on the brightside you have guys like us and tech manuals. Hope this might help you out a bit. Have a good one.