duramax stumbling

[bikernut]

have a 05 3500 4x4 and driving along the truck starts to stumble if feeding it fuel and then shuts down in the limp mode. I then hit the brake to stop and the truck returns to normal except check engine light stays on and runs fine for a while and then starts it all over again. Chevy dealer a while back found a chafed wire going to the fuel injector regulator and repaired and it was going great and then started acting up again, back to the dealer to check previous repair and everything was okay, they have tried a bunch of things but haven't found anything else, hoping some one has heard of this or experienced the same and can tell me what was done to solve it.
thanks