2001 Expedition with 4WD and engine surege issues

My 2001 Ford EB Expedition 4x4 goes into 4WD high by itself. No rhyme or reason why or when. Just a surprise when you try to go from a red light/stop sign, and you're unable to accelerate normally. My husband finally had the idea to shut off the engine (after several unsuccessful attempts to put the truck in 4WD and then back into AWD using the controls). Of course, we let the vehicle sit for approximately 3-4 hours. Have you heard of this before? Is it a computer issue?

The engine also surges occasionally. I've learned to be careful of how close I am to someone when stopped in a line, and I make sure I have my foot firmly on the brake. Today as I was stopping (that last second when the speedometer goes to zero) I happened to be looking at the controls as the engine decided to surge. The speedometer revved up to 70mph and the vehicle jumped forward slightly against my braking. This happened about 3 days after the 4WD incident. Could they be related?