I am experiencing an intermittent display of the following Engine, Trac Off, and Vsc lights. When they come on they stay on the whole time I am driving. Then the next time I drive the car they may stay off. Any suggestions. My Scion is a 2005 XB with 80,600 miles. Once before the Trac Off light stayed on and the dealer found a vacuum leak.

 

could be a dead alternator or dying battery

 

Look through this thread, it's a common issue with a number of causes.
https://www.scionlife.com/forums/maintenance-car-care-1604/check-engine-vsc-trac-off-lights-my-xb-10539/

I'd first start by resetting the ECU by either pulling the fuse or disconnecting the neg terminal on the battery for a few minutes.

You haven't added anything new to the car, right?