Engine Power Reduced / PO299 Code

[Desrtracer]

So this happened back in December while pulling my trailer up a grade in California the computer says Engine Power Reduced and it literally goes to a crawl.....I took it to the dealership to diagnose the problem and they said it was the Turbo Charger....I took it to a mechanic not wanting to spend the 5k the dealer wanted and the turbo was replaced...6 days after getting it back the same thing happened and he said the new Garrett turbo was faulty and full of oil so they replaced it......2 weeks later again pulling my trailer it does the same exact thing so I take it in after the weekend with my trailer so the mechanic can hook up his computer so we can drag the trailer around until it does it again which it does and it shows the veins are 100% open...he cleans out the manifolds and says that was the problem....I tested it again sunday pulled my trailer up this steep hill by my house twice with no issues so go back to my house shut the truck off and load my bikes and gear back in the trailer and head out to take it back to storage...getting on the freeway going up the ramp it shuts off again with the same problem so I lim it to storage shut the truck off for 10 mins unhook and then get back into the truck and all is back to normal and full power.....Now the previous times it sat for 6 hours and was back to normal, sat all of new years weekend and was fine and this last time 10 mins and it was fine...all of these have happened under load with my trailer behind it....I am 4k into this and I am still having the same problem so I am asking if anyone has any ideas?

This is a 2008 LT 2500
Stock other than lift and tires

[IdahoRob]

P0299 is an under boost code. When this code is thrown, it will put the turbo vanes to 100% to try and make up for the lack of boost. I would look for a boost leak. Look at all the boost tubes (turbo to intercooler and from intercooler to grid heater/throttle valve, and then to the engine) Could be any of these joints, there is also a cross over bridge between the intake runners on the heads that has a short intake elbow with an o'ring in it and that could of blown out.

[IdahoRob]

As you are posting in EFI Live's forum, I'm assuming you have efi. If this is the case you can disable the limp mode so you are not stranded, if the leak is not terrible, until you fix the issue.

[Desrtracer]

As you are posting in EFI Live's forum, I'm assuming you have efi. If this is the case you can disable the limp mode so you are not stranded, if the leak is not terrible, until you fix the issue.

To be honest I am not sure what EFI is I just found this forum as I was looking for answers to my problem. This has been going on since December 5th and the Diesel Shop I am taking it to still has not fixed the problem and I am just frustrated as I tow a ton and cannot with this problem. If I am not in the right place I apologize.

[djv86]

If your throwing an under boost code you could possibly have a skewed boost sensor that doesn't read accurately. Or like idahorob says a boost leak.

Or the egr could be stuck open partially allowing exhaust to recirculate which would be bypassing the turbo which would be causing it to produce less boost