Does it stumble a little first before it dies, or does it die like someone turned it off? A few simple things I would check (in order of most to least likely):
1) Carboned up throttle-body bore - Easily cleaned with throttle body cleaner and a plastic bristled brush. It doesn't take much fuel/carbon to throw things off. I have a GM vehicle that was dying and the tb was fuel 'gummed-up' pretty bad ..needed a good cleaning. This is routine maintenance.
2) Worn Spark plugs . Inspect and replace if necessary.
3) Worn out (or weak) MAF sensor. MAF sensors can become dust covered over time (or oil covered if you have a K&N filter) ...and they don't live forever anyway. They can put out a signal barely within the 'good' range so it won't throw a code, but yet can lead the computer to cause opreational issues, usually seen at idle. I've had this happen. Often a quick cleaning with MAF cleaner can help and restore it higher into the 'good' range. MAF cleaning is periodic maintenance. If you have a scanner you can see the voltage output and see it's output.
4) PCV valve plugged , not sealing, or cracked PCV hose (sucking raw air).
5) Vacuum hose leaks ..or Vacuum leak somewhere else.
6) Fuel pressure issues (weak/failing pump, etc)
7) EGR issues. I don't remember on the 4.7 pickups, but on my Jeep GC with a 4.7 the EGR pipes are made of plastic with molded rubber elbows and T's. Due to age and heat, they become brittle and can crack causing the EGR to suck in regular air. So these are worth checking.
I'm just throwing out things I've encountered, and on vehicles I've worked on. Could be a combo of 1-4 ..which are maintenance items that are easy to creep up on an owner. All of these are fairly simple to check and not expensive to resolve.
