Saw this code today. Merged onto the highway and rolled into the throttle as I went into the middle lane. Truck felt good and then very low on power. I then noticed the light on the dash. Checked the code and saw 299. It would only make about 5-6psi and very limited power. I drove home like this (about 5 minutes), cleared the code and all was good.

was it turbo charger underboost? change your low end response to low instead of lowest. this has made the code issue disappear.
(po299)

It was actually at the middle setting. I bumped it to the highest a few days ago. That is really noticeable. I went to pull away from the boat ramp after launching my jet ski. The truck jumped with just a little throttle. Actually surprized me :)

I had this same problem which occurred 9 times while trailering my 31' 5th wheel. I had the Edge set at level 1 with the responsiveness set also at 1, but it did not help. I also set the power level to stock and it still occurred. I got so fed up, I sent the entire unit back. I love the PPE tuner and have had zero problems, better fuel economy, and excellent results with or without pulling my trailer.

just talked with the engineer at edge, and was told that the (P0299) turbo underboost, and (P10101), mass air have been fixed. many testers have had this problem, which is why they test these products before they come out. The new ones will be shipped to testers by wednesday.

I had those same issues, but other than that, the truck flat goes with the edge w/ juice. 19.6 mpg from fresno to vegas!

i have a '04 gmc sierra 2500 hd ext cab w/duramax/allison. i don't know where to go for answers. i googled gm po299 and po116, this site came up. hope no one minds me asking for help. it certainly isn't coming from gm.
my trailer is a 19' aluminum 3000lb (loaded). the truck originally - going up hill (fairly steep) at about 55mph, would easily accelerate w/o downshifting. i noticed a problem when it down shifted on a fairly light grade at 65 set on cruise.
the truck had a substantial loss of power in august '04. this was after an oil change and fuel filter replacement in rapid city, SD. sept '04 service light came on onstar gave code po299 and other "low power" issue. i have a receipt from the dealer saying gm knows of code po299 and po116 (causing loss of power), software issue, no fix yet, but working on one.
in jan '05, just for the heck of it, i brought it to another dealer and they said they could reflash it. they did, no change in performance. it is a noticeable detriment. w/o pulling my trailer, the engine has to rev well above 2k to have any power. it has no low end torque. when it shifts up, it lugs, like it is going into too high of a gear. when hard accelerating, it has trouble holding a gear, sometimes shifts up and down and can't hold a gear. it is very noticeable when accelerating uphill.
in may '05 it was at two dealers, they stated it is fine and has 535 ft lbs of torque (according to their computer).
my selling dealer, general manager told me to just put in a banks six gun tuner and be done w/the gm programming issue, by overiding it. i also put in the 4" cat back exhaust, installed jan '06. this system only adds more fuel. i only used level 2. not pulling a trailer, i have driven a hilly area of highway and holding 75mph. the egt will stay almost to the red line of 1500-1600F unless i let off. under hard acceleration, foot to the floor almost, from a stop to 65 mph, it will go easily to 1300-1400F. turbo boost would be right up to 25-30+ psi.
when new, it would easily chirp the tires. now, i can put my foot to the floor from a stop and won't even chirp them.
i had to disconnect the banks 6 gun. 2 months ago, when up to operating temp, at highway speed, the truck would buck and sound like it was loading up and blow lots of smoke. the banks 6 gun was the culprit. it was disconnected and the truck back to the way it was before, that does not happen. the truck has operated the same w/or w/o the banks system.
i have been to arbitration w/the BBB. gm testified that when the truck was reflashed, it received the "fix" for po299 and po116. they specifically testified that at some point before january '05, they had a fix for these two codes and they "fixed" them at that time. i really think they are lying in that testimony. then when it went in for the same complaint 3 months later, they said it was fine. i think they lied and fabricated that detail. they never notified me, they said they would when a fix was available. so, i think they used the visit in jan '05 as convenient place to fabricate a repair to the problem.
i found code po116 online - something - cooling temp.
any advice out there? if nothing else, i'd like to share my heart ache of my $45k poor investment, so others can see how gm doesn't always have concern for their loyal customers (4th new gm truck i've owned, all dealer serviced).
jon