Recently had the 1998 TC LE repaired: valve cover gasket, brakes front and back and power steering pump. Everything is fine up to when premium fuel was added to a half tank of mid grade fuel. A burning odor developed about 8 miles from fill-up. I am taking the vehicle in for an inspection for fluid leaks possibly related to recent repairs or maybe a new problem. However, is it possible that the premium fuel is not combusting well enough to cause the odor and a power loss? A recent safety inspection deemed all OK after the repairs; but the odor is a cause of concern. What do you think?