What TK is referring to is the charge air sensor, or turbo boost sensor. It is a Bosch component and there was a large batch of defective ones covering a huge number of engines. There is a recall program where all sensors within a certain engine SN range should be replaced under warranty. If the engines in that 4300 Sovran fall into that range and have not had this recall service, they are due at no expense to the owner.
PM me if you need help looking up the specific engines.