Oh, just to let you guys know, we started using the fuel treatment that GM recommends (stanadyne, I think) and it has cleared up.

just started using fuel treatment? you shoulda been using that stuff since the first day you got that beast

It's not mine, and the old man says if it needed fuel treatment from the start, it should have been included in the purchase price. $49,000 for a pickup that won't run on what is in the pump "just ain't right". They are giving him the fuel treatment stuff, so I guess he can haggle better than I thought.

the stuff at the pump has changed since 2005

Fuel treatments don't just fix problems like this there is more to this.

I know you have the problem fixed but i was just told this story about a guy who had the same sorta problem , he just fueled up and the truck wouldnt go over 55.
He was told to take the fuel cap off and put it back on, He did it , it started running good , then it started doing the same thing again, he did the fuel cap again and it ran fine.....sometimes it the simple things..

sometimes it is weird how small stuff will change big things. About 8,000 miles on the odometer since starting fuel treatment, and not a peep out of it. I also have a 1948 jeep, never been opened up, thought I had a burned valve, ran a 20 ounce bottle of water through it at a trickle at 2000 rpm and my VERY BAD miss is gone. Just some carbon buildup.

Did they change the fuel filter during your visit at the dealer. If so, I would bet that was the problem.

Inform your father that anytime he has issues with the truck to always ask the dealer what the computer codes were.

I've never heard of an additive clearing anything up on our trucks after there was a problem. As stated, the #2 and #7 injector harness is also a possiblity.

I know it has been quite awhile since I posted this, but the problem started again about 6 months ago, and now I have 2 more that are doing the same thing. Never happens under a load, only empty. No codes, GM says computer is culprit, been replaced, no change. Is there a sensor that might cause this and not throw a code? The dealership got one freeze frame where something was out of whack but they have no idea what is causing it. Checked injector harness, it is all clean and tight.

a bad rail pressure sensor can cause the engine to die, randoly, when the truck is running and you unplug it the truck will die