I'm not sure about a 2005 but the newer trucks have electronic traction control, and what you describe sounds like it to a tee. It's designed to keep you from losing control on the highway if one or more wheels begin to slip by transferring power from the spinning wheel and/or applying the brakes. Is there a button on your dashboard to turn it off?
If you have it, I know in my truck I can disable it in 4WD by switching into 4 wheel then holding the ETC button down for about 10 seconds.