Possible limp mode?!?!?
 

So, doing about 70 on the highway, have about a quater tank of fuel, go to pass a slower car and bam, nothing. pressing the pedel and not even a rpm jump. engine stays the same rpm and speed doesnt increase. so i decel, at about 55 i press the pedel to the floor, i get a slight rpm jump but nothing like pedel to the floor rpm jump. it rev's to about 2000 and mph jumps to 65, so i exit, cause it sounds like the engine is starving for fuel. pull in to the gas station, check all the fuel lines, check the fuel filter to see if my previous prob had come back, nothing. Entire fuel sys was fine. i fill the tank, start up, and rev the engine and bam hits rev limiter no prob. so i say f'it and hop back on the highway, haven't had a prob since. (its been 3 days) throttle response is great, turbo spools fine, fuel filter is clean. oil is new (1400 miles) same with air filter. so any one heard of this? what should i look for? pc glitch? random prob?

do you have an airdog or FASS?

bone stock, minus the aluminum WIF sensor plug and a intake resinator delete.

Have you checked for any codes to see if it did actually limp?

didnt check for any silent codes. but i never got a C.E.L. so i dont know.

You can have codes without the CEL coming on. Kind of strange for it doing what it did, though.

Alright, Im a Duramax Mechanic at my local dealership. 4 things that will cause this.
#1 - Air filter(the factory Blue Donaldson Air filter will get clogged real quick replaced it and get something with a white filter element) this could have been your issue cause the turbo will actually tear the filter apart alowing air to bypass the fitler.
#2 - Fuel filter(you need to change your fuel filter at a maximum of every 15000 miles)
#3 - EGR Valve(this will become clogged in 2006 and up, the factory will reprogram your ECM to allow the dealer to clean your EGR valve with the Tech 2).
#4 - Injector Harness break( your engine will go into limp mode and only run on 4 cylinders. it will have a reall lound crackle sound like starting it on ether. This is a porblem on all lly and lbz engine. #2 and & 7 injector connectors gets replaced. GM sells a kit to lengthen the harness do it is not in a bind pulling the pins out of the connectorL

#4 sounds like your problem. it can come and go. but it will always come back.

could be #4 cause it did act like that, but it didnt make the clank niose. it just refused to make any power, and rpm any anything. it just ran like it was starving for fuel or air. i had a four wheeler that did the same thing but i dont want to treat my truck like a quad. quad turned out to need the injector cleaned. but i put injector cleaner in the truck before we left on the trip. changed the oil and filter. and air filter. from what i gather i have to go get the codes checked, cause it guess it can throw a code with out throwing the CEL

yes its possible.

I just had this happen to my car (volvo). It was really cold out and the thing had no power at all. Put it in neutral and she would hit the limiter but in gear it had nothing. The last couple days its been about 40 out and I went to move the car and it was fine. Not really sure what the problem was.