GMC Repair: 2005 2500 Dermax diesel 160000km, speedy reply, power message

Question
QUESTION: I have a loss of power problem, after driving down the highway and pulling my trailer I lose the throttle, it will only rev to 2000 and seems to run rough I have an automatic transmission in trailer tow mode, I pull over shut the motor off, wait a couple minutes, starts and runs fine for an hour or so then does it again, replaced fuel filter seemed to run better, but did it again after an hour or so, just started pulling this trailer and just recently had hitch and trailer brake installed never has done it not pulling the trailer, has no rime or reason uphill, downhill on flat highway, please help going on holidays next week with grandson. Thanks Todd

ANSWER: Hi
Does the service engine soon light OR Reduced Engine Power
message appear on the DIC?
Please let me know ASAP.
Pawl

---------- FOLLOW-UP ----------

QUESTION: No lights or anything come on at all and all gauges read the same as always thanks for your speedy reply

Answer
Hi
At this timwe, my best advice would be to take it to a repair shop that is familiar with the 6.6 Duramax, and have them scan the PCM and see if any codes are stored.
If not, it REALLY sounds like there is a fuel issue, either not enough fuel or it is "sucking air".
The latter I  have run into, ONLY when vehicle was trailering. There was a plastic fuel line from the top of tank, to a metal line on the front of tank.
Would not leak when empty or bed  weight.
When he hooked up his trailer (gooseneck) and loaded it with farm equipment, it would stall, loose throttle, etc... all different symptoms.
I would go look back there, if there is ANY, ANY signs of wetness, even seepage that IS not hitting ground, look REALLY close at that line.
I hope thios helps, and sorry for the delay.
Good luck
Pawl