Toyota Repair: 2006 Land Cruiser, toyota land cruisers, scantool

Question
My wife and I have two, yes two 2006 Toyota Land Cruisers.  My is perfect 130K miles, my wife's has been a nightmare, 110K miles.  It started with a VSC light coming on.  The dealer said it was a defective gas cap, twice!  Although we finally got the light off the car acts as if the differential is locked.  For example, the steering is poor and dangerous.  If you hit a bump at 50 mph watch out, the car will jump when the two tires reconnect with the road.  The car will literally swerve off the road.  The dealer says this is in our minds, but we have two of these cars - same year, and know how they are supposed to drive.  Please help.  How do we fix this problem.

Answer
The way to fix the problem is to go to another toyota dealer, they sound like they don't want to be bothered with your problem, first of all the VSC/TRAC light coming on is not because of a loose gas cap, there is a problem with these systems and the first step would be to connect the diagnostic scantool to see what the trouble codes are, there is no doubt from what you told me that there is a problem which could be a safety issue so if the dealer you are going to says that this is in your minds then  you need to go elsewhere and have someone that actually cares and is willing to deal with this problem diagnose this, maybe you could take a technician on a roadtest to demonstrate what is happening.