Hi i have a 2003 gmc yukon denali 6.0 , automatic 180,000 miles I've owned for about 4 yrs first time seeing this. 

I've been having code p1516 and reduce engine power with service stability on the dash display and car goes into limp mode.

I just get the scanner and clear the code, turn the truck back on and it'll be fine for a while but for safety I don't drive on the expressway because the code pops up more often than street driving. 

What also happened other than the code is from time to time I stop at a stop sign and go I get a traction active and I lose all power in the gas pedal and I have to let go of the gas pedal momentarily (a couple seconds) and press the gas again and it disappears from the display and drives normal again. might these 2 issues be related? Do I replace the module related to the code p1516? can it be an electrical issue? I've seen people install new ground wires with additional grounds to have more power. The reduce engine power is really the issue that I need to figure out Please help!!!