My coworker has a 2001 Yukon thats dies once it gets to normal temp, between 10-15 minutes of turning it on.

Basically it will either sputter and then die completly and not restart, sounds like a bad misfire, once you start it up again it will run fine for the rest of the trip everytime, its always in the first 15 minutes.

Any ideas? its got the 7.? liter maybe its a 8.1...its the biggest they had in 01. It does not happen everytime, we just tried the scantool on it and it works fine. no codes.

So its about 50% of the time, we will try to reproduce the problem in about an hour.