While I was away for work my wife had the truck and it crapped out on her. It wouldn't go past 2nd gear and 25 mph. Called GM and they towed it to the nearest dealer.

These are the codes that I got from them:
P0401-insufficient EGR flow
P0106-MAP sensor performance
P0101-MAF sensor performance

The truck is stock with no tunes. I have modified the airbox slightly, got rid of some of the housing before the filter. The dealer noted that but agreed with me that shouldn't have anything to do with it. They reflashed the ECM and everything is fine.

Would like to get some feedback and opinions, think this is a wierd thing probably won't be repeated or does it sound like a possible bad ground?

Thanks for your help and ideas,

Was she driving in any nasty snowstorms? There have been a couple reports of the maf sensor icing up and screwing up the readings in those conditions. Check the clamp that attaches the intake mouthpiece to the turbo, mine was loose and caused the p0101 code. The p0401 could be the egr valve starting to act up.