well, this is not my truck, but when driving it if you accelerate and then let off, it dies. also dies when going around corners. also surges at idle. It starts fine, and the owner recently replaced all the metal fuel lines, which is apparently when the problem started. I have no experience with the 6.2, but have experience with other non gm diesels. any help would be appreciated. thanks!

Maybe air. Does it die while in neutral when you rev it up and then let off?

yes, however, I went and played with it for a little bit and have solved the problem. One question though, as you are looking at the engine, on the left side of the IP is a little screw, that goes through some kind of valve. it affected the Idle when I would push it forward, but I do not think it was the idle control..what does this thing do?:)