Well, they found oil leaks on the driver and passenger side valve covers. They also found a slow leak in the right-front tire from a bad bead seal when they reinstalled the wheels/tires after getting them repaired. Hopefully that resolves my issues and I have no more surprises.

Thanks for the info guys. If I hadn't pointed them to the valve covers who knows how many visits I would have needed for them to track down the burning smell.

-Spencer