Re: Steering wobble
As RS said, check the tires, especially for unusual wear and especially if they were just installed, then perhaps to the alignment shop to double check the alignment and suspension for wear. A wobble that starts when you hit a bump usually indicates wear, but your truck is low mileage and the suspension should not be worn.
Catskinners right on too, something is wrong (duh!), and steering stabilizers might just mask the problem until it gets worse. Best to identify and fix the problem then add a new stabilizer to prevent premature wear.
You didn't mention if your truck is 4WD, but I run dual Rancho steering stabilizers on an '04 4WD Excursion, mainly because it sees a lot of off-road in Baja. I am happy with the Ranchos, but I have never tried others, so I cannot compare.