Power Surge/Jerking Under Moderate Load

Over the passed few days I noticed my truck was jerking and hesitating under load. It happens in 3rd 4th and 5th gear at around 2000-2500 RPM. It lasts for about 3 seconds then picks up. Under heavy loads it seems fine (boosting as well). I searched and found similar threads and kind of have an idea where to start to diagnose this problem. However one thing I discovered that the other threads I found didn't really mention is that the timing drops VERY low when it happens (hence the jerking and power loss). I was able to watch the reading from my scan gauge and saw the timing drop to 0 degrees for one surge and -6 for another. What could be making the ECU retard the timing this much intermittently under moderate loads? I have the 7th injector kit from URD and have done some tunning with the timing. The current map however has been fine for the past 20k miles. I think I'm gonna go back to the stok map from URD and see if this helps. Any other ideas?