Weird power issue
 

Had the strangest thing happen today. This is EXACTLY what happened. Started my 08' 2500 w/ 26,220 mi and moved to the other side of driveway. 3-5 min run time. Sat for about 1/2 hr and started again to go to dump. As always, I pushed the exhaust break button and started down the driveway. Once on the pavement the darn truck had no power. Acted like it didnt want to shift due to not being able to gain enough rpm's, I guess. Would depress the peddle and it would gain little to nothing. Went about 1 1/4 mi and it started operating just fine. Only thing unusual that occurred today is when I push the exhaust break button you can normally hear a change in the sound the engine is making. Kind of a groan. This morning that 'groan' was way more obvious than normal. I played with the exhaust break button and tow/haul mode as I drove and everything appeared to be just fine. Truck is completely stock and other than the occassional CEL and a couple turbo cleanings, I havent had any issues at all. Has this happened to anyone of you? Is it possible the exhaust break was stuck open, or something like that?

I had a similar issue a few months ago. Turns out the EGR was stopped up.