2011 Honda Pilot Suv What cause the Steering wheel to shimmy?

Classic symptom of warped brake rotors. Replace the front rotors. If the pads are worn out, replace them too, or leave them if they still have a lot of meat on them. It wouldn't hurt to flush and bleed the brakes.

will the rotor cause it to pull to the left? i was about to buy this vehicle the asking price is $7,900 odometer: 163000 miles what you think about the price and miles on this vehicle?

Sounds like you have warped front brake rotors. Get premium brake pads and new rotors. 

Both front rotors need to be turned to flatten them (as the wheels are connected by the steering assembly) so one  wheel's hiccup also effects the other wheel.

. Mechanic know when you describe the problem to him and can quote the cost of turning the rotors and the cost of new rotors.  I am not saying "new rotors are flat" either. It could be that or the fact that maybe you need new pads.  Mechanic can tell when he "SEES" them.

Fit new rotors and pads. Machining rotors will cost almost as much as new ones and there is a safety limit to the minimum thickness.

When was the last time you had the wheels aligned?  

Front rotors need to be turned, but it could be a loose front-end part that is exacerbating the problem so the front end components will need to be checked if you haven' had an alignment in a while.