P2127 Intermittent Failure
 

I'm having a randomly reoccurring problem with my '07 Avalanche LT with a 5.3L (non-flex fuel) engine. At random times, it throws a P2127 DTC (sometimes P2138 as well) and immediately reduces power and disables Stabiltrak. Once I clear the DTC this doesn't happen again for months and other times it happens multiple times in a single day. P2127 is specific to the Accelerator Pedal so I replaced it but that didn't solve the problem. I then replaced the Throttle Body & TPS but that didn't solve it either. I've saw a few TSBs that said to look for corrosion near the left kick panel but that looks fine as well.

I actually had my graphing ODB2 tool on the truck (APP Circuit E circuit) during a failure where I did see a very brief drop in voltage, which likely what's triggering the P2127 DTC. I also had a DVM on the 5V reference line, during a different failure time, and I was not able to catch the drop in voltage on my DVM as it's an extremely brief event. My best theory is that the 5V reference voltage is being shunted to ground (by some other sensor) but it happens so fast that I can't determine what's causing this problem.

It's a very random failure that tends to only happen during warmer days (>85F). I've also seen some sites that claim that the Fuel Tank Pressure sensor can cause this but I don't want to pull the tank unless I have too. Has anyone encounter this crazy issue before that might be able to point into the root cause? Thanks in advance!