Besides the ignition switch issue which you can somewhat rule out if you use a single key rather than a key chain that swings to and fro check the cam angle sensor and crank angle sensors. They go bad with age. Their job is to send 'information" to the ECM [computer] so it can adjust fuel and air mix based on their inputs. You can begin by simply seeing if the connector and pins are engaged. Plug and unplug a couple of times, if you don't have electrical contract cleaner simply use some WD 40 on the pins. There is also a throttle position sensor. Go to this link and you will find the locations referenced.

http://wiki.answers.com/Q/Where_is_crank...

#1. Change the fuel filter first.

#2. Ask a Chevrolet Dealer to test the fuel pressure on the fuel rail pressure fitting beside the fuel injector nozzles. This is a very inexpensive test BUT the fuel filter must be clean to get an accurate fuel pressure reading.

Check the ignition module. They are famous for failing when they get hot and then start working again after a short cool down. Typically get worse over time.

Hope no one is making a left hand turn in front of you when it happens again. Only an idiot would keep driving it. I hope there are no small children around that could be victims of your stupidity. Will it really matter if I tell you what is wrong with it? You're going to take it to a mechanic anyway. The cost to fix it will be certainly less than buying another truck. BTW, it's probably the ignition recall that's already killed 13. Look it up. If you want to be #14, keep driving it.

Could be your fuel mixture not enough gas or too much air and too much gas or check ur butterfly because they can sometimes get stuck causing the engine to shut off

Assuming no codes then it points to a failing computer or fuel pump.

My truck shuts off while driving all lights stay on and radio stays on but engine shuts off and the truck falls out of gear and yet the truck says it's in drive, gives no warring. Has happened 8 times in the last week and today I turned my lights on and radio shut off and turns back on! Try it to see if I can figure it out before I take it some where! It's my only vehicle so this can't keep happening HELP!